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A test for the two-stage thermoinactivation model for chymotrypsin

Biomedical Sciences Research Institute Computer Science Research Institute Environmental Sciences Research Institute Nanotechnology & Advanced Materials Research Institute

Owusu, RK and Berthalon, N (1993) A test for the two-stage thermoinactivation model for chymotrypsin. Food Chemistry, 48 (3). p. 231. [Journal article]

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URL: http://dx.doi.org/10.1016/0308-8146(93)90132-Y

DOI: doi:10.1016/0308-8146(93)90132-Y

Abstract

Chymotrypsin was irreversibly inactivated at 30–130°C, pH 1.0–7.0 and in the presence of 0–4.0 m guanidine hydrochloride (GnHCl). The activation enthalpy for enzyme thermoinactivation (Δ#) at moderate temperatures, pH 4.0–7.0 and in ≤2 m GnHcl was 175–322 kJ mol−1. The activation entropy (ΔS#) was 244–734 J mol−1 K−1. Such results are compatible with enzyme unfolding being the rate-determining step for the thermoinactivation of native chymotrypsin. For chymotrypsin pre-unfolded at low pH, high temperature and/or in Gn/HCl, ΔH# was 30–40 kJ mol−1 and ΔS# was between −182 and −191 J mol−1 K−1. Therefore, thermoinactivation of pre-unfolded chymotrypsin is likely to involve covalent bond lysis as the rate-determining step. A biphasic Arrhenius plot was obtained for chymotrypsin thermoinactivation in 1.0–1.5 m GnHCl. Taken together, these results provide strong support for the two-stage model for enzyme thermoinactivation.

Item Type:Journal article
Faculties and Schools:Faculty of Life and Health Sciences
Faculty of Life and Health Sciences > School of Biomedical Sciences
Research Institutes and Groups:Biomedical Sciences Research Institute
Biomedical Sciences Research Institute > Northern Ireland Centre for Food and Health (NICHE)
ID Code:16899
Deposited By:Dr Richard Owusu-Apenten
Deposited On:01 Feb 2011 13:28
Last Modified:01 Feb 2011 13:28

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