Open AccessPorcine Carboxypeptidase B
Author(s) -
Sokolovsky Mordechai
Publication year - 1972
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1972.tb01693.x
Subject(s) - tetranitromethane , carboxypeptidase , nitration , residue (chemistry) , chemistry , tyrosine , peptide , carboxypeptidase a , biochemistry , stereochemistry , enzyme , organic chemistry
Porcine carboxypeptidase B is inhibited rapidly by nitration with an eight‐fold molar excess of tetranitromethane. Enzymie activity towards both basic and non‐basic substrates falls to less than 30% of the control. The loss of activity correlates with the nitration of a single tyrosyl residue. The nitrotyrosyl‐containing peptide as isolated had the sequence Thr‐Ile‐Tyr‐Pro‐Ala, homologous to the peptide containing tyrosine‐248 in the active‐center sequence of bovine carboxypeptidase A. The nitrotyrosyl residue has an apparent pK of 7.5 (compared to 6.3 for the corresponding residue in carboxypeptidase A) indicating a difference in the microenvironment of nitrocarboxypeptidase B and nitrocarboxypeptidase A.