Open AccessALKALINE PH DEPENDENCE OF δCHYMOTRYPSIN-CATALYZED HYDROLYSIS OF SPECIFIC SUBSTRATES
Author(s) -
Pablo Valenzuela,
Myron L. Bender
Publication year - 1969
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.63.4.1214
Subject(s) - chymotrypsin , chemistry , hydrolysis , tryptophan , ionic strength , catalysis , alpha chymotrypsin , tyrosine , enzyme , medicinal chemistry , stereochemistry , biochemistry , organic chemistry , trypsin , amino acid , aqueous solution
Km (app) andk cat for the δchymotrypsin-catalyzed hydrolysis ofN -acetyl-L-tryptophan methyl ester andN -furylacryloyl-L-tryptophanamide were measured as a function of pH and ionic strength. TheKm (app) values do not increase considerably above pH 9 for δ-chymotrypsin, as is the case with α-chymotrypsin. The observed kinetic difference between both enzymes at high pH suggests that the reversible inactivation of α-chymotrypsin at alkaline pH may involve the participation of tyrosine 146 or alanine 149 since both residues are present as chain termini in α-chymotrypsin but not in δ-chymotrypsin.