Carboxypeptidase Y from Saccharomyces cerevisiae. Conformational differences reflected in kinetic behaviour in water and deuterium oxide.
Biochim Biophys Acta
; 706(1): 141-3, 1982 Aug 23.
Article
em En
| MEDLINE
| ID: mdl-6289903
The glycoenzyme carboxypeptidase Y (peptidyl--amino-acid hydrolase, EC 3.4.16.1), from baker's yeast (British Fermentation Products Strain, Ng 72), of molecular weight 60 000, had a protein portion closely similar to those in the literature for carboxypeptidase Y isolations from other yeast sources, but was 25.3 wt% carbohydrate (mannose 83.3% by wt., glucosamine 10.3% by wt. with traces of galactose and galactosamine). Circular dichroic spectra indicated that the enzyme lost its beta-structure as the pH was lowered from 8.08 to 4.16. At p2H 8.22 in 2H2O media the conformation of this enzyme was different from that observed at pH 8.08. A tyrosine residue appeared to be perturbed by lowering the pH of the medium. Carboxypeptidase Y was rapidly, and essentially irreversibly, inactivated at low p2H. The pH profile of kcat for the carboxypeptidase Y-catalysed hydrolysis of 4-nitrophenyltrimethylacetate showed two inflections at 45 degrees C: one at pKapp approximately 3.7 insensitive to temperature variation (ascribed to a carboxyl group), and one of pKapp approximately 5.7 markedly temperature-dependent and possibly caused by a histidine residue.
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Base de dados:
MEDLINE
Assunto principal:
Saccharomyces cerevisiae
/
Carboxipeptidases
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Água
/
Deutério
Idioma:
En
Revista:
Biochim Biophys Acta
Ano de publicação:
1982
Tipo de documento:
Article