The beta hairpin structural motif

Structural motif

In a chain-like biological molecule, such as a protein or nucleic acid, a structural motif is a supersecondary structure, which appears also in a variety of other molecules...

 is the simplest 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...

 motif involving two beta strands that look like a hairpin

Hairpin

A hair pin or hairpin is a long device used to hold a person's hair in place.Hairpins made of metal, ivory, bronze, carved wood, etc. were used in ancient Assyria and Egypt for securing decorated hairstyles. Such hairpins suggest, as graves show, that many were luxury objects among the Egyptians...

. The motif consists of two strands that are adjacent in primary structure

Primary structure

The primary structure of peptides and proteins refers to the linear sequence of its amino acid structural units. The term "primary structure" was first coined by Linderstrøm-Lang in 1951...

 oriented in an antiparallel

Antiparallel (biochemistry)

In biochemistry, two molecules are antiparallel if they run side-by-side in opposite directions or when both strands are complimentary to each other....

 arrangement (where the N-terminus of one sheet is adjacent to the C-terminus of the next) and linked by a short loop of two to five amino acid

Amino acid

Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...

s. Beta hairpins can occur in isolation or as part of a series of hydrogen bond

Hydrogen bond

A hydrogen bond is the attractive interaction of a hydrogen atom with an electronegative atom, such as nitrogen, oxygen or fluorine, that comes from another molecule or chemical group. The hydrogen must be covalently bonded to another electronegative atom to create the bond...

ed strands that collectively comprise a beta sheet.

Researchers such as Francisco Blanco

Francisco J. Blanco

Francisco Jose Blanco is a structural biologist working as Group Leader at the Centro de investigación Cooperativa en biociencias CIC bioGUNE. His research utilizes Nuclear Magnetic Resonance spectroscopy to characterize [protein structure] and protein folding...

 et al. have used protein NMR to show that beta-hairpins can be formed from isolated short peptide

Peptide

Peptides are short polymers of amino acid monomers linked by peptide bonds. They are distinguished from proteins on the basis of size, typically containing less than 50 monomer units. The shortest peptides are dipeptides, consisting of two amino acids joined by a single peptide bond...

s in aqueous solution, suggesting that hairpins could form nucleation sites for protein folding

Protein folding

Protein folding is the process by which a protein structure assumes its functional shape or conformation. It is the physical process by which a polypeptide folds into its characteristic and functional three-dimensional structure from random coil....

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