Specificity and stereospecificity of alpha-chymotrypsin.
1. The optically pure p-nitrophenyl esters of the d and l enantiomers of N-acetyl-tryptophan, N-acetylphenylalanine and N-acetyl-leucine, and the p-nitrophenyl ester of N-acetylglycine, have been prepared. 2. These materials are all substrates of alpha-chymotrypsin, and the rates of deacylation of the corresponding acyl-alpha-chymotrypsins have been determined. 3. As the size of the amino acid side chain increases, the l series deacylate progressively faster than the N-acetylglycyl-enzyme, and the d series progressively more slowly. 4. The results are interpreted in terms of a three-locus model of the enzyme's active site, which accounts for the interrelationship between substrate specificity and stereospecificity observed. 5. The concepts of negative specificity and of specificity saturation are introduced.
D001665:Binding Sites; D055598:Chemical Phenomena; D002621:Chemistry; D002918:Chymotrypsin / Q000378:metabolism*; D005998:Glycine; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007930:Leucine; D008956:Models, Chemical; D009596:Nitrophenols / Q000138:chemical synthesis*; D010649:Phenylalanine; D014364:Tryptophan
D009596:Nitrophenols; D010649:Phenylalanine; D014364:Tryptophan; D002918:Chymotrypsin; D007930:Leucine; D005998:Glycine