Open AccessPorcine Carboxypeptidase B
Author(s) -
Sokolovsky Mordechai,
Eisenbach Lea
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.tb01719.x
Subject(s) - tyrosine , carboxypeptidase a , residue (chemistry) , carboxypeptidase , chemistry , stereochemistry , active site , enzyme , peptide , biochemistry , active center , amino acid residue , circular dichroism , exopeptidase , peptide sequence , gene
Coupling of porcine carboxypeptidase B with diazotized arsanilic acid labels an active‐site tyrosine residue of the enzyme. Tyrosine modification is accompanied by a change in the activities of carboxypeptidase B towards both basic and non‐basic substrates. The major arsanilazotyrosine‐containing peptide, Thr‐Ile‐Tyr‐Pro‐Ala, isolated by affinity chromatography is homologous with the peptide containing tyrosine‐248 from the active center of bovine carboxypeptidase A. Formation of the arsanilazotyrosine residue generates extrinsic Cotton effects above 300 nm. The dichroic spectrum of the azochromophore constitutes a sensitive probe of conformational changes accompanying the interaction of arsanilazocarboxypeptidase B with inhibitors, as monitored by changes in the circular dichroic spectrum. The changes are consistent with the hypothesis that the tyrosine residue is a component of the active‐site region.