When the polypeptide chain of protein molecule forms the spatial conformation, it often has 180 ° turn back (turning), and the structure at the turning back is called β - corner structure.
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yesPolypeptide chainCommon inSecondary structure, ConnectproteinSecondary structure in molecule（Alpha helixandBeta folding）, makePeptide chainA non repetitive polypeptide region with altered trend, generally containing 2 to 16Amino acid residue。Corners containing more than 5 amino acid residues are also called loops.The common corners contain four amino acid residues, and there are two types.
4 amino acid residues:
In the fouraminoIn acid, the firstamino acidOfcarboxylIt forms a hydrogen bond with the amino acid of the fourth amino acid.glycineandprolineIt is easy to appear in this structure.In some proteins, there is also a β - corner structure formed by three consecutive amino acidscarbonylA hydrogen bond is formed between oxygen and the imino hydrogen of the third amino acid.
2 types:
Corner I is characterized by: the firstAmino acid residueCarbonyl oxygen and the fourthResidueOfamideHydrogen bond is formed between hydrogen;The third residue of Corner II is often glycine.The second residue in these two corners is mostly proline.
X-ray of more than 580 proteinsCrystal diffractionIt is found that some proteins are almost completely composed ofAlpha helical structureSome proteins are almost all composed of β-Folding structureThe α - helix and β - fold structures exist in some protein molecules.
