Structural changes in the transformation from α- to β-keratin
Recently deduced structure patterns for α-keratin (the protein in hair) and β-keratin (produced by stretching α-keratin) are described. In the transformation the intramolecular hydrogen bonds and the crosslinks between the helical chains are broken. The molecular chain helices are extended until there is just one residue per helix turn. New laterally oriented interchain hydrogen bonds are formed. They are in planes making dihedral angles of about 120° with each other. These hydrogen bonds produce aggregates that can be “6-stacks”, shaped like hexagonal prisms, or perhaps (with half of the chains reversing their helix rotation sense) “pleated” or “wavy” sheets or composites of these or other types. In any case, disulfide and presumably other types of crosslinks are formed between appropriately located carbon atoms at the bends of the hydrogen bond aggregates.
KeywordsHexagonal Prism Helical Chain Helix Axis Axial Shift Helix Turn
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