Abstract

High-sensitivity differential scanning calorimetry has been applied to the study of porcine pancreatic carboxypeptidase B, the proenzyme and its 81-residue activation domain. The thermal study has been carried out over a range of scan rates, ionic strengths and pH values. The thermal unfolding of the isolated activation domain has been found to be reversible and corresponds to that of a typical compact globular structure, with melting temperatures higher than those of the enzyme and proenzyme. Both proteins, on the other hand, undergo an irreversible, highly scan-rate-dependent thermal denaturation under all the experimental conditions investigated. The denaturation of the enzyme at pH 7.5 and the proenzyme at pH 7.5 and 9.0 follows the two-state irreversible model [Sánchez-Ruiz, J.M., López-Lacomba, J.L., Cortijo, M. & Mateo, P.L. (1988) Biochemistry 27, 1648-1652]. Thus the kinetic constants and activation parameters of the denaturation process could be obtained and compared to those for other proteins, particularly those of the closely related carboxypeptidase A system. Study holds ProTherm entries: 7515, 7516, 7517, 7518, 7519, 7520, 7521, 7522, 7523, 7524, 7525, 7526, 7527, 7528, 7529, 7530, 7531, 7532, 7533, 7534, 7535, 7536, 7537, 7538, 7539, 7540, 7541, 7542, 7543, 7544, 7545, 7546 Extra Details: activation domain; compact globular structure;,scan-rate-dependent; kinetic constants

Submission Details

ID: THQRMZSm3

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:34 p.m.

Version: 1

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