Thermal inactivation and product inhibition of Aspergillus terreus CECT 2663 alpha-L-rhamnosidase and their role on hydrolysis of naringin solutions.
Biosci Biotechnol Biochem
; 66(7): 1442-9, 2002 Jul.
Article
em En
| MEDLINE
| ID: mdl-12224626
The kinetics of thermal inactivation of A. terreus alpha-rhamnosidase was studied using the substrate p-nitrophenyl alpha-L-rhamnoside between 50 degrees C and 70 degrees C. Up to 60 degrees C the inactivation of the purified enzyme was completely reversible, but samples of crude or partially purified enzyme showed partial reversibility. The presence of the product rhamnose, the substrate naringin, and other additives reduced the reversible inactivation, maintaining in some cases full enzyme activity at 60 degrees C. A mechanism for the inactivation process, which permitted the reproduction of experimental results, was proposed. The products rhamnose (inhibition constant, 2.1 mM) and prunin (2.6 mM) competitively inhibited the enzyme reaction. The maximum hydrolysis of supersaturated naringin solution, without enzyme inactivation, was observed at 60 degrees C. Hydrolysis of naringin reached 99% with 1% naringin solution, although the hydrolysis degree of naringin was only 40% due to products inhibition when the initial concentration of flavonoid was 10%. The experimental results fitted an equation based on the integrated Michaelis-Menten's, including competitive inhibition by products satisfactorily.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Plantas
/
Aspergillus
/
Flavonoides
/
Flavanonas
/
Glicosídeo Hidrolases
Idioma:
En
Revista:
Biosci Biotechnol Biochem
Assunto da revista:
BIOQUIMICA
/
BIOTECNOLOGIA
Ano de publicação:
2002
Tipo de documento:
Article
País de afiliação:
Argentina
País de publicação:
Reino Unido