ISSN:
0006-3592
Keywords:
thermoinactivation of enzymes
;
protein stability
;
stabilization
;
covalent modification
;
Chemistry
;
Biochemistry and Biotechnology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
Based on the idea that proteins can be stabilized by a decrease in the thermodynamically unfavorable contact of the hydrophobic surface clusters with water, α-chymotrypsin (CT) was acylated with carboxylic acid anhydrides or re-ductively alkylated with aliphatic aldehydes. Modification of CT with hydrophilic reagents leads to 100-1000-fold increase in stability against the irreversible thermoinactivation. The correlation holds: the greater the hydrophilization increment brought about by the modification, the higher is the protein thermostability. After some limiting value, however, a further increase in hydrophilicity does not change thermostability.It follows from the dependence of the thermoinactivation rate constants on temperature that for hydrophilized CT there is the conformational transition at 55-65°C into an unfolded state in which inactivation is much slower than that of the low-temperature conformation. The thermodynamic analysis and fluorescent spectral data confirm that the slow inactivation of hydrophilized CT at high temperatures proceeds via a chemical mechanism rather than Incorrect refolding operative for both the native and low-temperature form of the modified enzyme. Hence, the hydrophilization stabilizes the unfolded high-temperature conformation by eliminating the incorrect refolding. © 1992 John Wiley & Sons, Inc.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bit.260400603
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