ISSN:
0022-3832
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The principles of protein structure may be stated as follows: (1) Proteins are composed primarily of long polypeptide chain molecules. (2) In natural proteins, only levo orientations are present. (3) The distances between adjacent bonded atoms and the angles between adjacent bonds are approximately the same as in comparable small molecules. (4) Hydrogen bonds are formed wherever possible. (5) Like atomic groups tend to be surrounded by close neighbors in a like manner. (6) Atoms, atomic groups, and molecules tend to pack as closely as possible. These principles, first published by the writer in 1943, have been amply verified by subsequent developments. Their application is illustrated by brief consideration of the structures of silk, polyglycine II, α- and β-polypeptides, α- and β-keratin, and collagen. It is proposed that in α-keratin the polypeptide helices are grouped (not coiled) into triplets, triple-triplets or “nonets,” and 27-chain groups, to give most efficient packing of the side chains. For collagen, a single chain helical molecule is proposed, with hydrogen bonds forming 10-atom rings and with the residues in groups of three. One residue of each group, it is suggested, is pro, hypro, asp, or glu, with the last two types existing as rings, formed either by condensation or by hydrogen-bonding.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1958.1203012102
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