Open AccessThe Cleavage of Prolyl Peptides by Kidney Peptidases
Author(s) -
Dehm Peter,
Nordwig Arnold
Publication year - 1970
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1970.tb01175.x
Subject(s) - chemistry , sephadex , carboxypeptidase , biochemistry , chromatography , size exclusion chromatography , carboxypeptidase a , trypsin , residue (chemistry) , peptide bond , proline , enzyme , amino acid
Carboxypeptidase activity was detected in swine kidney microsomes. The enzyme was solubilised by treatment with trypsin and toluene. Approximately 330‐fold purification was achieved by subsequent chromatography on DEAE‐cellulose and hydroxylapatite. As shown by polyacrylamide gel investigation, the carboxypeptidase preparation thus obtained was practically pure. It still contains trace impurities of aminopeptidase M which is quite similar in physical properties. The molecular weight of the carboxypeptidase was 240000 as determined by Sephadex gel filtration. It is activated by manganese ions and exhibits a pH‐optimum at 7.75. The carboxypeptidase preferentially attacks substrates with a prolyl residue in the last but one position. No chain length dependence was found. Peptides free of proline were also cleaved, but normally at a rather low rate. The designation carboxypeptidase P (indicating its preference of proline peptide bonds) is therefore suggested. The physiological role of the new peptidase is discussed.