title: Kinetic studies on the mechanism and the specificity of peptide semisynthesis catalyzed by the serine proteases alpha-chymotrypsin and beta-trypsin.
abstract: The mechanism of peptide semisynthesis catalyzed by alpha-chymotrypsin and beta-trypsin has been investigated. The dependence of the apparent ratio of the second order rate constants for the deacylation of the acyl-enzyme intermediate by water and other nucleophiles (amino acid amides) on the nucleophile concentration indicates a mechanism that involves two acyl-enzymes. One with and one without bound nucleophile that both can be deacylated by water. The nucleophile specificity in peptide semisynthesis catalyzed by the proteases was found to reflect the P1-specificity in the corresponding hydrolytic reaction.
mesh_terms: D000215:Acylation; D000596:Amino Acids / Q000378:metabolism; D002918:Chymotrypsin / Q000378:metabolism*; D006868:Hydrolysis; D007700:Kinetics; D010452:Peptide Biosynthesis; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D014357:Trypsin / Q000378:metabolism*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D000596:Amino Acids; D014443:Tyrosine; C007651:ethyl N-alpha-acetyl-tyrosinate; D002918:Chymotrypsin; D014357:Trypsin