CHAINS OF ALTERNATING SULFUR AND π-BONDED ATOMS IN EIGHT SMALL PROTEINS

This paper demonstrates the existence of regions in eight small globular proteins in which the side chains of sulfur‐containing amino acids (cysteine and methionine) alternate in space with side chains of aromatic amino acids (histidine, phenylalanine, tryptophan and tyrosine). The proteins are: rubredoxin, high potential iron protein, cytochrome c, flavodoxin, deoxyhemoglobin, trypsin inhibitor, ribonuclease‐S, and lysozyme. The sulfur‐φ‐bonded ‘chains’ involve a minimum of five and a maximum of 10 amino acids, and contain the most polarizable atoms within proteins. S‐φ‐chains give extra stability to the folding of proteins; they may also afford paths for the step‐wise movement of electrons.