In a crude extract of baker's carboxypeptidase Y is predominantly found in an inactive form. A procedure for the isolation of the inactive form of the enzyme is presented. It is shown that the inactive form is identical to the reconstituted complex of carboxypeptide Y with its inhibitor. This complex is stable above pH 5, i.e., it remains inactive between pH 5 and 9. The conversion to the active enzyme occurs below pH 5, also in the absence of proteolytic enzymes. The inhibitor of carboxypeptidase Y can be removed enzymatically from the complex by treatment with @entity46452 (EC 3.4.22.9) at pH 7. At pH 5, the carboxypeptidase Y-inhibitor complex is activated both by @entity21756 (EC 3.4.23.6) and @entity375 proteinases are activated in a crude extract by incubation at pH 5 [3]. Based on the levels of @entity70363 in an activated extract and on the time required for conversion to active carboxypeptidase Y, @entity46452 is at least 10-times more effective than @entity21756 . Peptides that arise during the pH 5-incubation procedure did not accelerate the proteolytic activation of carboxypeptidase Y. The inhibitor of carboxypeptidase Y is completely degraded in the proteolytic activation steps, no accumulation of intermediates is observed. Only one form of active carboxypeptidase Y is found to be present in the proteolytically activated extracts, i.e., no polypeptide fragments of carboxypeptidase Y-inhibitor remain bound to the enzyme after it has been activated by @entity46452 . In vacuoles prepared from spheroplasts no inactive carboxypeptidase Y can be detected.

Interaction of proteinases and their inhibitors from XXXX . Activation of carboxypeptidase Y.

@entity70363 :: ('855949;856649', 'Gene') :: ['proteinase A and B'] @entity375 :: ('4932', 'Species') :: ['B. Yeast'] @entity21756 :: ('855949(Tax:4932)', 'Gene') :: ['proteinase A'] @entity46452 :: ('856649(Tax:4932)', 'Gene') :: ['proteinase B']
@entity375 :: (4932,Species) :: ['yeast']
