Photoprotein
Encyclopedia
Photoproteins refer to bioluminescent proteins from luminous organisms. These proteins do not exhibit a luciferin
-luciferase
reaction, that is, a normal enzyme
-substrate
reaction. Instead, these proteins display luminescence proportional to the amount of the protein. Such proteins are stable as a luciferin-photoprotein complex, often until the addition of another required factor, such as Ca2+
for the photoprotein aequorin
.
The term was first used to describe the unusual chemistry of the Chaetopterus
luminescent system.
Luciferin
Luciferins are a class of light-emitting biological pigments found in organisms that cause bioluminescence...
-luciferase
Luciferase
Luciferase is a generic term for the class of oxidative enzymes used in bioluminescence and is distinct from a photoprotein. One famous example is the firefly luciferase from the firefly Photinus pyralis. "Firefly luciferase" as a laboratory reagent usually refers to P...
reaction, that is, a normal enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
-substrate
Substrate (biochemistry)
In biochemistry, a substrate is a molecule upon which an enzyme acts. Enzymes catalyze chemical reactions involving the substrate. In the case of a single substrate, the substrate binds with the enzyme active site, and an enzyme-substrate complex is formed. The substrate is transformed into one or...
reaction. Instead, these proteins display luminescence proportional to the amount of the protein. Such proteins are stable as a luciferin-photoprotein complex, often until the addition of another required factor, such as Ca2+
Calcium in biology
Calcium plays a pivotal role in the physiology and biochemistry of organisms and the cell. It plays an important role in signal transduction pathways, where it acts as a second messenger, in neurotransmitter release from neurons, contraction of all muscle cell types, and fertilization...
for the photoprotein aequorin
Aequorin
Aequorin is a photoprotein isolated from luminescent jellyfish and a variety of other marine organisms...
.
The term was first used to describe the unusual chemistry of the Chaetopterus
Chaetopterus
Chaetopterus or the parchment worm or parchment tube worm is a genus of marine polychaete worm that lives in a tube it constructs in sediments or attaches to a rocky or coral reef substrate. The common name arises from the parchment-like appearance of the tubes the worm lives in...
luminescent system.