R. Henderson
Dec 14, 1970
Citations
3
Influential Citations
287
Citations
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Journal
Journal of molecular biology
Abstract
The structure of indoleacryloyl-α-chymotrypsin, based on crystallographic studies at 2.5 A resolution, is described. The indolyl part of the acyl group binds deeply in the hydrophobic pocket which accommodates the aromatic side chains of N-formyl-l-tryptophan and N-formyl-l-phenylalanine. The over-all structure closely resembles that of tosyl-α-chymotrypsin. In particular, a water molecule is hydrogen bonded both to the carbonyl oxygen of the acyl group and to the imidazole of His-57. It is suggested that this water molecule may function as the nucleophile in deacylation. This interpretation leads to a plausible model for the stereochemistry of the hydrolytic mechanism of the enzyme.