Abstract
Examination of .beta.-carbon coordinates of seryl, aspartyl and histidyl residues in active sites of .alpha.-chymotrypsin and subtilisin BPN'' shows tha a close geometrical arrangement can be obtained in an antiparallel .beta.-structure. Therefore some polypeptides incorporating serine, aspartic acid and histidine, poly (Gly-Ser-Asp-His-Ala-Pro) and poly [(Asp-Leu-Asp-Leu)10, (His-Leu-Ser-Leu)1], and expected to have some tendency to give rise to an antiparallel .beta.-conformation, were prepared and studied. The second polymer only adopts a fairly well-defined .beta.-structure in aqueous solution. Catalytic activities of these products towards p-nitrophenyl acetate are not improved as compared to histidine. However, kinetic pK of histidine side-chain depends markedly upon the nature of the product, owing probably to a hydrophobic environment effect.