Study of the thermal stability of D-amino acid oxidase fromTrigonopsis variabilisreveals enzyme inactivation via multiple steps

Autor:	Pavel Ačai, Waander Riethorst, Bernd Nidetzky, Anita Slavica
Rok vydání:	2006
Předmět:	chemistry.chemical_classification Oxidase test biology Chemistry Stereochemistry D-amino acid oxidase Biochemistry Catalysis Dissociation (chemistry) Cofactor chemistry.chemical_compound Reaction rate constant Enzyme Potassium phosphate biology.protein Partial oxidation Biotechnology
Zdroj:	Biocatalysis and Biotransformation. 24:426-436
ISSN:	1029-2446 1024-2422
DOI:	10.1080/10242420601034025
Popis:	The thermal stability of a highly purified preparation of D-amino acid oxidase from Trigonopsis variabilis (TvDAO), which does not show microheterogeneity due to the partial oxidation of Cys-108, was studied based on dependence of temperature (20–60°C) and protein concentration (5–100 µmol L−1). The time courses of loss of enzyme activity in 100 mmol L−1 potassium phosphate buffer, pH 8.0, are well described by a formal kinetic mechanism in which two parallel denaturation processes, partial thermal unfolding and dissociation of the FAD cofactor, combine to yield the overall inactivation rate. Estimates from global fitting of the data revealed that the first-order rate constant of the unfolding reaction (ka) increased 104-fold in response to an increase in temperature from 20 to 60°C. The rate constants of FAD release (kb) and binding (k−b) as well as the irreversible aggregation of the apo-enzyme (kagg) were less sensitive to changes in temperature, their activation energy (Ea) being about 52 kJ mol−1 in ...
Databáze:	OpenAIRE
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