Bioinorganic chemistry
Overview
Bioinorganic chemistry is a field that examines the role of metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

s in biology. Bioinorganic chemistry includes the study of both natural phenomena such as the behavior of metalloprotein
Metalloprotein
Metalloprotein is a generic term for a protein that contains a metal ion cofactor. Metalloproteins have many different functions in cells, such as enzymes, transport and storage proteins, and signal transduction proteins. Indeed, about one quarter to one third of all proteins require metals to...

s as well artificially introduced metals, including those that are non-essential, in medicine and toxicology. Many biological process
Biological process
A biological process is a process of a living organism. Biological processes are made up of any number of chemical reactions or other events that results in a transformation....

es such as respiration
Cellular respiration
Cellular respiration is the set of the metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate , and then release waste products. The reactions involved in respiration are catabolic reactions that involve...

 depend upon molecules that fall within the realm of inorganic chemistry
Inorganic chemistry
Inorganic chemistry is the branch of chemistry concerned with the properties and behavior of inorganic compounds. This field covers all chemical compounds except the myriad organic compounds , which are the subjects of organic chemistry...

. The discipline also includes the study of inorganic models or mimics that imitate the behaviour of metalloproteins.

As a mix of biochemistry
Biochemistry
Biochemistry, sometimes called biological chemistry, is the study of chemical processes in living organisms, including, but not limited to, living matter. Biochemistry governs all living organisms and living processes...

 and inorganic chemistry
Inorganic chemistry
Inorganic chemistry is the branch of chemistry concerned with the properties and behavior of inorganic compounds. This field covers all chemical compounds except the myriad organic compounds , which are the subjects of organic chemistry...

, bioinorganic chemistry is important in elucidating the implications of electron-transfer protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

s, substrate bindings and activation, atom and group transfer chemistry as well as metal properties in biological chemistry.
About 99% of mammals' mass are the elements carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

, nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

, calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...

, sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...

, chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

, potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...

, hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

, phosphorus
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...

, oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 and sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

.
Encyclopedia
Bioinorganic chemistry is a field that examines the role of metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

s in biology. Bioinorganic chemistry includes the study of both natural phenomena such as the behavior of metalloprotein
Metalloprotein
Metalloprotein is a generic term for a protein that contains a metal ion cofactor. Metalloproteins have many different functions in cells, such as enzymes, transport and storage proteins, and signal transduction proteins. Indeed, about one quarter to one third of all proteins require metals to...

s as well artificially introduced metals, including those that are non-essential, in medicine and toxicology. Many biological process
Biological process
A biological process is a process of a living organism. Biological processes are made up of any number of chemical reactions or other events that results in a transformation....

es such as respiration
Cellular respiration
Cellular respiration is the set of the metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate , and then release waste products. The reactions involved in respiration are catabolic reactions that involve...

 depend upon molecules that fall within the realm of inorganic chemistry
Inorganic chemistry
Inorganic chemistry is the branch of chemistry concerned with the properties and behavior of inorganic compounds. This field covers all chemical compounds except the myriad organic compounds , which are the subjects of organic chemistry...

. The discipline also includes the study of inorganic models or mimics that imitate the behaviour of metalloproteins.

As a mix of biochemistry
Biochemistry
Biochemistry, sometimes called biological chemistry, is the study of chemical processes in living organisms, including, but not limited to, living matter. Biochemistry governs all living organisms and living processes...

 and inorganic chemistry
Inorganic chemistry
Inorganic chemistry is the branch of chemistry concerned with the properties and behavior of inorganic compounds. This field covers all chemical compounds except the myriad organic compounds , which are the subjects of organic chemistry...

, bioinorganic chemistry is important in elucidating the implications of electron-transfer protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

s, substrate bindings and activation, atom and group transfer chemistry as well as metal properties in biological chemistry.

Composition of living organisms

About 99% of mammals' mass are the elements carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

, nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

, calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...

, sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...

, chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

, potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...

, hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

, phosphorus
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...

, oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 and sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

. The organic compound
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

s (proteins, lipids and carbohydrates) contain the majority of the carbon and nitrogen and most of the oxygen and hydrogen is present as water. The entire collection of metal-containing biomolecules in a cell is called the metallome.

History

Paul Ehrlich
Paul Ehrlich
Paul Ehrlich was a German scientist in the fields of hematology, immunology, and chemotherapy, and Nobel laureate. He is noted for curing syphilis and for his research in autoimmunity, calling it "horror autotoxicus"...

 used organoarsenic (“arsenicals”) for the treatment of syphilis
Syphilis
Syphilis is a sexually transmitted infection caused by the spirochete bacterium Treponema pallidum subspecies pallidum. The primary route of transmission is through sexual contact; however, it may also be transmitted from mother to fetus during pregnancy or at birth, resulting in congenital syphilis...

, demonstrating the relevance of metals, or at least metalloids, to medicine, that blossomed with Rosenberg’s discovery of the anti-cancer activity of cisplatin
Cisplatin
Cisplatin, cisplatinum, or cis-diamminedichloroplatinum is a chemotherapy drug. It is used to treat various types of cancers, including sarcomas, some carcinomas , lymphomas, and germ cell tumors...

 (cis-PtCl2(NH3)2). The first protein ever crystallized (see James B. Sumner
James B. Sumner
James Batcheller Sumner was an American chemist. He shared the Nobel Prize in Chemistry in 1946 with John Howard Northrop and Wendell Meredith Stanley.-Biography:...

) was urease
Urease
Urease is an enzyme that catalyzes the hydrolysis of urea into carbon dioxide and ammonia. The reaction occurs as follows:In 1926, James Sumner showed that urease is a protein. Urease is found in bacteria, yeast, and several higher plants. The structure of urease was first solved by P.A...

, later shown to contain nickel at its active site
Active site
In biology the active site is part of an enzyme where substrates bind and undergo a chemical reaction. The majority of enzymes are proteins but RNA enzymes called ribozymes also exist. The active site of an enzyme is usually found in a cleft or pocket that is lined by amino acid residues that...

. Vitamin B12
Cyanocobalamin
Cyanocobalamin is an especially common vitamer of the vitamin B12 family. It is the most famous vitamer of the family, because it is, in chemical terms, the most air-stable...

, the cure for pernicious anemia
Pernicious anemia
Pernicious anemia is one of many types of the larger family of megaloblastic anemias...

 was shown crystallographically by Dorothy Crowfoot Hodgkin
Dorothy Crowfoot Hodgkin
Dorothy Mary Hodgkin OM, FRS , née Crowfoot, was a British chemist, credited with the development of protein crystallography....

 to consist of a cobalt in a corrin
Corrin
Corrin is an heterocyclic compound. It is the parent macrocycle related to substituted derivative that is found in vitamin B12. Its name reflects that it is the "core" of vitamin B12 .-Coordination chemistry:...

 macrocycle. The Watson-Crick structure for DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

 demonstrated the key structural role played by phosphate-containing polymers.

Themes in bioinorganic chemistry

Several distinct systems are of identifiable in bioinorganic chemistry. Major areas include:

Metal ion transport and storage

This topic covers a diverse collection of ion channel
Ion channel
Ion channels are pore-forming proteins that help establish and control the small voltage gradient across the plasma membrane of cells by allowing the flow of ions down their electrochemical gradient. They are present in the membranes that surround all biological cells...

s, ion pumps (e.g. NaKATPase), vacuole
Vacuole
A vacuole is a membrane-bound organelle which is present in all plant and fungal cells and some protist, animal and bacterial cells. Vacuoles are essentially enclosed compartments which are filled with water containing inorganic and organic molecules including enzymes in solution, though in certain...

s, siderophore
Siderophore
Siderophores are small, high-affinity iron chelating compounds secreted by grasses and microorganisms such as bacteria and fungi...

s, and other protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

s and small molecules which control the concentration of metal ions in the cells. One issue is that many metals that are metabolically required are not readily available owing to solubility or scarcity. Organisms have developed a number of strategies for collecting such elements and transporting them.

Enzymology

Many reactions in life sciences involve water and metal ions are often at the catalytic centers (active sites) for these enzymes, i.e. these are metalloprotein
Metalloprotein
Metalloprotein is a generic term for a protein that contains a metal ion cofactor. Metalloproteins have many different functions in cells, such as enzymes, transport and storage proteins, and signal transduction proteins. Indeed, about one quarter to one third of all proteins require metals to...

s. Often the reacting water is a ligand (see metal aquo complex
Metal aquo complex
Metal aquo complexes are coordination compounds containing metal ions with only water as a ligand. These complexes are the predominant species in aqueous solutions of many metal salts, such as metal nitrates, sulfates, and perchlorates. They have the general stoichiometry [Mn]z+. Their behavior...

). Examples of hydrolase
Hydrolase
In biochemistry, a hydrolase is an enzyme that catalyzes the hydrolysis of a chemical bond. For example, an enzyme that catalyzed the following reaction is a hydrolase:-Nomenclature:...

 enzymes are carbonic anhydrase
Carbonic anhydrase
The carbonic anhydrases form a family of enzymes that catalyze the rapid interconversion of carbon dioxide and water to bicarbonate and protons , a reversible reaction that occurs rather slowly in the absence of a catalyst...

, metallophosphatase
Phosphatase
A phosphatase is an enzyme that removes a phosphate group from its substrate by hydrolysing phosphoric acid monoesters into a phosphate ion and a molecule with a free hydroxyl group . This action is directly opposite to that of phosphorylases and kinases, which attach phosphate groups to their...

s, and metalloproteinase
Metalloproteinase
Metalloproteinases constitute a family of enzymes from the group of proteases, classified by the nature of the most prominent functional group in their active site. These are proteolytic enzymes whose catalytic mechanism involves a metal. Most metalloproteases are zinc-dependent, but some use...

s. Bioinorganic chemist seek to understand and replicate the function of these metalloproteins.

Metal-containing electron transfer proteins are also common. They can be organized into three major classes: iron-sulfur protein
Iron-sulfur protein
Iron-sulfur proteins are proteins characterized by the presence of iron-sulfur clusters containing sulfide-linked di-, tri-, and tetrairon centers in variable oxidation states...

s (such as rubredoxin
Rubredoxin
Rubredoxins are a class of low-molecular-weight iron-containing proteins found in sulfur-metabolizing bacteria and archaea. Sometimes rubredoxins are classified as iron-sulfur proteins; however, in contrast to iron-sulfur proteins, rubredoxins do not contain inorganic sulfide.Like cytochromes,...

s, ferredoxin
Ferredoxin
Ferredoxins are iron-sulfur proteins that mediate electron transfer in a range of metabolic reactions. The term "ferredoxin" was coined by D.C. Wharton of the DuPont Co...

s, and Rieske protein
Rieske protein
Rieske proteins are iron-sulfur protein components of cytochrome bc1 complexes and cytochrome b6f complexes which were first discovered and isolated by John S. Rieske and co-workers in 1964. It is a unique [2Fe-2S] cluster in that one of the two Fe atoms is coordinated by two histidine residues...

s), blue copper proteins
Copper proteins
Copper proteins are proteins that contain one or more copper ions as prosthetic groups. The metal centres in the copper proteins can be classified into several types:...

, and cytochrome
Cytochrome
Cytochromes are, in general, membrane-bound hemoproteins that contain heme groups and carry out electron transport.They are found either as monomeric proteins or as subunits of bigger enzymatic complexes that catalyze redox reactions....

s. These electron transport proteins are complementary to the non-metal electron transporters nicotinamide adenine dinucleotide
Nicotinamide adenine dinucleotide
Nicotinamide adenine dinucleotide, abbreviated NAD, is a coenzyme found in all living cells. The compound is a dinucleotide, since it consists of two nucleotides joined through their phosphate groups. One nucleotide contains an adenine base and the other nicotinamide.In metabolism, NAD is involved...

 (NAD) and flavin adenine dinucleotide (FAD).

Oxygen transport and activation proteins

Aerobic life make extensive use of metals such as iron, copper, and manganese. Heme
Heme
A heme or haem is a prosthetic group that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin. Not all porphyrins contain iron, but a substantial fraction of porphyrin-containing metalloproteins have heme as their prosthetic group; these are...

 is utilized by red blood cell
Red blood cell
Red blood cells are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system...

s in the form of hemoglobin
Hemoglobin
Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates, with the exception of the fish family Channichthyidae, as well as the tissues of some invertebrates...

 for oxygen transport and is perhaps the most recognized metal system in biology. Other oxygen transport systems include myoglobin
Myoglobin
Myoglobin is an iron- and oxygen-binding protein found in the muscle tissue of vertebrates in general and in almost all mammals. It is related to hemoglobin, which is the iron- and oxygen-binding protein in blood, specifically in the red blood cells. The only time myoglobin is found in the...

, hemocyanin
Hemocyanin
Hemocyanins are respiratory proteins in the form of metalloproteins containing two copper atoms that reversibly bind a single oxygen molecule . Oxygenation causes a color change between the colorless Cu deoxygenated form and the blue Cu oxygenated form...

, and hemerythrin
Hemerythrin
Hemerythrin is an oligomeric protein responsible for oxygen transport in the marine invertebrate phyla of sipunculids, priapulids, brachiopods, and in a single annelid worm, magelona. Recently, hemerythrin was discovered in methanotrophic bacterium Methylococcus capsulatus...

. Oxidase
Oxidase
An oxidase is any enzyme that catalyzes an oxidation-reduction reaction involving molecular oxygen as the electron acceptor. In these reactions, oxygen is reduced to water or hydrogen peroxide ....

s and oxygenase
Oxygenase
An oxygenase is any enzyme that oxidizes a substrate by transferring the oxygen from molecular oxygen O2 to it. The oxygenases form a class of oxidoreductases; their EC number is EC 1.13 or EC 1.14....

s are metal systems found throughout nature that take advantage of oxygen to carry out important reactions such as energy generation in cytochrome c oxidase
Cytochrome c oxidase
The enzyme cytochrome c oxidase or Complex IV is a large transmembrane protein complex found in bacteria and the mitochondrion.It is the last enzyme in the respiratory electron transport chain of mitochondria located in the mitochondrial membrane...

 or small molecule oxidation in cytochrome P450 oxidase
Cytochrome P450 oxidase
The cytochrome P450 superfamily is a large and diverse group of enzymes. The function of most CYP enzymes is to catalyze the oxidation of organic substances. The substrates of CYP enzymes include metabolic intermediates such as lipids and steroidal hormones, as well as xenobiotic substances...

s or methane monooxygenase
Methane monooxygenase
Methane monooxygenase, or MMO, is an enzyme capable of oxidizing the C-H bond in methane as well as other alkanes. Methane monooxygenase belongs to the class of oxidoreductase enzymes ....

. Some metalloproteins are designed to protect a biological system from the potentially harmful effects of oxygen and other reactive oxygen-containing molecules such as hydrogen peroxide
Hydrogen peroxide
Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...

. These systems include peroxidase
Peroxidase
Peroxidases are a large family of enzymes that typically catalyze a reaction of the form:For many of these enzymes the optimal substrate is hydrogen peroxide, but others are more active with organic hydroperoxides such as lipid peroxides...

s, catalase
Catalase
Catalase is a common enzyme found in nearly all living organisms that are exposed to oxygen, where it catalyzes the decomposition of hydrogen peroxide to water and oxygen...

s, and superoxide dismutase
Superoxide dismutase
Superoxide dismutases are a class of enzymes that catalyze the dismutation of superoxide into oxygen and hydrogen peroxide. As such, they are an important antioxidant defense in nearly all cells exposed to oxygen...

s. A complementary metalloprotein to those that react with oxygen is the oxygen evolving complex
Oxygen evolving complex
The oxygen-evolving complex, also known as the water-splitting complex, is a water-oxidizing enzyme involved in the photooxidation of water during the light reactions of photosynthesis. Based on a widely accepted theory from 1970 by Kok, the complex can exist in 5 states: S0 to S4. Photons trapped...

 present in plants. This system is part of the complex protein machinery that produces oxygen
Oxygen evolution
Oxygen evolution is the process of generating molecular oxygen through chemical reaction. Mechanisms of oxygen evolution include the oxidation of water during oxygenic photosynthesis, electrolysis of water into oxygen and hydrogen, and electrocatalytic oxygen evolution from oxides and...

 as plants perform photosynthesis
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...

.

Bioorganometallic chemistry

Bioorganometallic
Bioorganometallic chemistry
Bioorganometallic chemistry is the study of biologically active molecules that contain carbon directly bonded to metals or metalloids. This area straddles the fields of organometallic chemistry, biochemistry, and medicine. It is subset of bioinorganic chemistry. Naturally occurring...

 systems includes the hydrogenase
Hydrogenase
A hydrogenase is an enzyme that catalyses the reversible oxidation of molecular hydrogen . Hydrogenases play a vital role in anaerobic metabolism....

s and methylcobalamin as examples of naturally occurring organometallic compounds. This area is more focused on the utilization of metals by unicellular organisms. Bioorganometallic compounds are significant in environmental chemistry
Environmental chemistry
Environmental chemistry is the scientific study of the chemical and biochemical phenomena that occur in natural places. It should not be confused with green chemistry, which seeks to reduce potential pollution at its source...

.
  • The nitrogen cycle
    Nitrogen cycle
    The nitrogen cycle is the process by which nitrogen is converted between its various chemical forms. This transformation can be carried out by both biological and non-biological processes. Important processes in the nitrogen cycle include fixation, mineralization, nitrification, and denitrification...

      make extensive use of metals for the redox interconversions. Nitrogenase
    Nitrogenase
    Nitrogenases are enzymes used by some organisms to fix atmospheric nitrogen gas . It is the only known family of enzymes that accomplish this process. Dinitrogen is quite inert because of the strength of its N-N triple bond...

    , an Fe-Mo-S protein, is one of the more famous metalloprotein
    Metalloprotein
    Metalloprotein is a generic term for a protein that contains a metal ion cofactor. Metalloproteins have many different functions in cells, such as enzymes, transport and storage proteins, and signal transduction proteins. Indeed, about one quarter to one third of all proteins require metals to...

    s associated with nitrogen metabolism. More recently, the cardiovascular and neuron
    Neuron
    A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...

    al importance of nitric oxide
    Nitric oxide
    Nitric oxide, also known as nitrogen monoxide, is a diatomic molecule with chemical formula NO. It is a free radical and is an important intermediate in the chemical industry...

     has been examined, including the enzyme nitric oxide synthase
    Nitric oxide synthase
    Nitric oxide synthases are a family of enzymes that catalyze the production of nitric oxide from L-arginine. NO is an important cellular signaling molecule, having a vital role in many biological processes...

    . (See also: nitrogen assimilation
    Nitrogen assimilation
    Nitrogen assimilation is a fundamental biological process that occurs in plants and algae that are incapable of independent nitrogen fixation. The assimilation of nitrogen has marked effects on plant productivity, biomass, and crop yield, and nitrogen deficiency leads to a decrease in structural...

    .)

Metals in medicine

A surprising number of drugs contain metals. This theme relies ons the study of the design and mechanism of action of metal-containing pharmaceuticals, and compounds that interact with endogenous metal ions in enzyme active sites. This diverse field includes the platinum and ruthenium anti-cancer drugs (e.g. cisplatin
Cisplatin
Cisplatin, cisplatinum, or cis-diamminedichloroplatinum is a chemotherapy drug. It is used to treat various types of cancers, including sarcomas, some carcinomas , lymphomas, and germ cell tumors...

), chelating agents, gold drug chaperones, and gadolinium contrast agent
MRI contrast agent
MRI contrast agents are a group of contrast media used to improve the visibility of internal body structures in magnetic resonance imaging . The most commonly used compounds for contrast enhancement are gadolinium-based. MRI contrast agents alter the relaxation times of tissues and body cavities...

s. Lithium carbonate
Lithium carbonate
Lithium carbonate is a chemical compound of lithium, carbon, and oxygen with the formula Li2CO3. This colorless salt is widely used in the processing of metal oxides and has received attention for its use in psychiatry. It is found in nature as the rare mineral zabuyelite.-Properties:Like almost...

 has been used to treat the manic phase of bipolar disorder. Antiarthritic drugs, e.g. auranofin
Auranofin
Auranofin is a gold complex classified by the World Health Organization as an antirheumatic agent.It has the brand name Ridaura.-Use in HIV infection:...

 are based on gold.

Environmental chemistry

Environmental chemistry traditionally emphasizes the interaction of heavy metals with organisms. Methylmercury
Methylmercury
Methylmercury is an organometallic cation with the formula . It is a bioaccumulative environmental toxicant.-Structure:...

 has caused major disaster called Minamata disease
Minamata disease
', sometimes referred to as , is a neurological syndrome caused by severe mercury poisoning. Symptoms include ataxia, numbness in the hands and feet, general muscle weakness, narrowing of the field of vision and damage to hearing and speech. In extreme cases, insanity, paralysis, coma, and death...

. Arsenic poisoning
Arsenic poisoning
Arsenic poisoning is a medical condition caused by increased levels of the element arsenic in the body. Arsenic interferes with cellular longevity by allosteric inhibition of an essential metabolic enzyme...

 is a widespread problem owing largely to arsenic contamination of groundwater
Arsenic contamination of groundwater
Arsenic contamination of groundwater is a natural occurring high concentration of arsenic in deeper levels of groundwater, which became a high-profile problem in recent years due to the use of deep tubewells for water supply in the Ganges Delta, causing serious arsenic poisoning to large numbers of...

, which affects many millions of people in developing countries. The metabolism of mercury- and arsenic-containing compounds involves cobalamin-based enzymes.

Alkali and alkaline earth metals

The abundant inorganic elements act as ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...

ic electrolyte
Electrolyte
In chemistry, an electrolyte is any substance containing free ions that make the substance electrically conductive. The most typical electrolyte is an ionic solution, but molten electrolytes and solid electrolytes are also possible....

s. The most important ions are sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...

, potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...

, calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...

, magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...

, chloride
Chloride
The chloride ion is formed when the element chlorine, a halogen, picks up one electron to form an anion Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides. The chloride ion, and its salts such as sodium chloride, are very soluble in water...

, phosphate
Phosphate
A phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...

, and the organic ion bicarbonate
Bicarbonate
In inorganic chemistry, bicarbonate is an intermediate form in the deprotonation of carbonic acid...

. The maintenance of precise gradients across cell membrane
Cell membrane
The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...

s maintains osmotic pressure
Osmotic pressure
Osmotic pressure is the pressure which needs to be applied to a solution to prevent the inward flow of water across a semipermeable membrane....

 and pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...

. Ions are also critical for nerve
Nerve
A peripheral nerve, or simply nerve, is an enclosed, cable-like bundle of peripheral axons . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons. Nerves are found only in the peripheral nervous system...

s and muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...

s, as action potential
Action potential
In physiology, an action potential is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a consistent trajectory. Action potentials occur in several types of animal cells, called excitable cells, which include neurons, muscle cells, and...

s in these tissues are produced by the exchange of electrolytes between the extracellular fluid
Extracellular fluid
Extracellular fluid usually denotes all body fluid outside of cells. The remainder is called intracellular fluid.In some animals, including mammals, the extracellular fluid can be divided into two major subcompartments, interstitial fluid and blood plasma...

 and the cytosol
Cytosol
The cytosol or intracellular fluid is the liquid found inside cells, that is separated into compartments by membranes. For example, the mitochondrial matrix separates the mitochondrion into compartments....

. Electrolytes enter and leave cells through proteins in the cell membrane called ion channels. For example, muscle contraction
Muscle contraction
Muscle fiber generates tension through the action of actin and myosin cross-bridge cycling. While under tension, the muscle may lengthen, shorten, or remain the same...

 depends upon the movement of calcium, sodium and potassium through ion channels in the cell membrane and T-tubule
T-tubule
A T-tubule is a deep invagination of the sarcolemma, which is the plasma membrane, only found in skeletal and cardiac muscle cells...

s.

Transition metals

The transition metal
Transition metal
The term transition metal has two possible meanings:*The IUPAC definition states that a transition metal is "an element whose atom has an incomplete d sub-shell, or which can give rise to cations with an incomplete d sub-shell." Group 12 elements are not transition metals in this definition.*Some...

s are usually present as trace element
Trace element
In analytical chemistry, a trace element is an element in a sample that has an average concentration of less than 100 parts per million measured in atomic count, or less than 100 micrograms per gram....

s in organisms, with zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...

 and iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

 being most abundant. These metals are used in some proteins as cofactors
Cofactor (biochemistry)
A cofactor is a non-protein chemical compound that is bound to a protein and is required for the protein's biological activity. These proteins are commonly enzymes, and cofactors can be considered "helper molecules" that assist in biochemical transformations....

 and are essential for the activity of enzymes such as catalase
Catalase
Catalase is a common enzyme found in nearly all living organisms that are exposed to oxygen, where it catalyzes the decomposition of hydrogen peroxide to water and oxygen...

 and oxygen-carrier proteins such as hemoglobin
Hemoglobin
Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates, with the exception of the fish family Channichthyidae, as well as the tissues of some invertebrates...

. These cofactors are bound tightly to a specific protein; although enzyme cofactors can be modified during catalysis, cofactors always return to their original state after catalysis has taken place. The metal micronutrients are taken up into organisms by specific transporters and bound to storage proteins such as ferritin
Ferritin
Ferritin is a ubiquitous intracellular protein that stores iron and releases it in a controlled fashion. The amount of ferritin stored reflects the amount of iron stored. The protein is produced by almost all living organisms, including bacteria, algae and higher plants, and animals...

 or metallothionein
Metallothionein
Metallothionein is a family of cysteine-rich, low molecular weight proteins. They are localized to the membrane of the Golgi apparatus...

 when not being used.

Main group compounds

Many other elements aside from metals are bio-active. Sulfur and phosphorus are required for all life. Phosphorus is almost exclusively exists as phosphate and its various ester]]s. Sulfur exists in a variety of oxidation states, ranging from sulfate (SO42-) down to sulfide (S2-). Selenium is a trace element involved in proteins that are antioxidants.

External links


Some books on bioinorganic chemistry

  • Heinz-Bernhard Kraatz (editor), Nils Metzler-Nolte (editor), Concepts and Models in Bioinorganic Chemistry, John Wiley and Sons, 2006, ISBN 3-527-31305-2
  • Ivano Bertini, Harry B. Gray, Edward I. Stiefel, Joan Selverstone Valentine, Biological Inorganic Chemistry, University Science Books, 2007, ISBN 1-891389-43-2
  • Wolfgang Kaim, Brigitte Schwederski "Bioinorganic Chemistry: Inorganic Elements in the Chemistry of Life." John Wiley and Sons, 1994, ISBN 0-471-94369-X
  • Rosette M. Roat-Malone, Bioinorganic Chemistry : A Short Course, Wiley-Interscience
    John Wiley & Sons
    John Wiley & Sons, Inc., also referred to as Wiley, is a global publishing company that specializes in academic publishing and markets its products to professionals and consumers, students and instructors in higher education, and researchers and practitioners in scientific, technical, medical, and...

    , 2002, ISBN 0-471-15976-X
  • J.J.R. Fraústo da Silva and R.J.P. Williams, The biological chemistry of the elements: The inorganic chemistry of life, 2nd Edition, Oxford University Press
    Oxford University Press
    Oxford University Press is the largest university press in the world. It is a department of the University of Oxford and is governed by a group of 15 academics appointed by the Vice-Chancellor known as the Delegates of the Press. They are headed by the Secretary to the Delegates, who serves as...

    , 2001, ISBN 0-19-850848-4
  • Lawrence Que, Jr., ed., Physical Methods in Bioinorganic Chemistry, University Science Books, 2000, ISBN 1-891389-02-5

  • Physiology
    Physiology
    Physiology is the science of the function of living systems. This includes how organisms, organ systems, organs, cells, and bio-molecules carry out the chemical or physical functions that exist in a living system. The highest honor awarded in physiology is the Nobel Prize in Physiology or...

  • Cofactor
    Cofactor (biochemistry)
    A cofactor is a non-protein chemical compound that is bound to a protein and is required for the protein's biological activity. These proteins are commonly enzymes, and cofactors can be considered "helper molecules" that assist in biochemical transformations....

  • Iron metabolism
    Human iron metabolism
    Human iron metabolism is the set of chemical reactions maintaining human homeostasis of iron. Iron is an essential element for most life on Earth, including human beings. The control of this necessary but potentially toxic substance is an important part of many aspects of human health and disease...

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