Kinetic study of the oxidation of gamma-L-glutaminyl-4-hydroxybenzene catalyzed by mushroom (Agaricus bisporus) tyrosinase.
J Agric Food Chem
; 47(9): 3495-502, 1999 Sep.
Article
em En
| MEDLINE
| ID: mdl-10552675
Despite the importance of the substrate gamma-L-glutaminyl-4-hydroxybenzene (GHB) in the melanin biosynthesis pathway in mushrooms Agaricus bisporus, the kinetics of its oxidation catalyzed by tyrosinase has never been properly characterized. For this purpose GHB and its corresponding o-diphenol (GDHB) were isolated and purified from A. bisporus mushrooms. The kinetic constants that characterize the action of tyrosinase on GHB and GDHB are = 2.10 +/- 0.10 microM/min, = 0.30 +/- 0.03 mM, = 210.0 +/- 7.3 microM/min, and = 7.80 +/- 0.41 mM. The oxygen kinetic constants for tyrosinase in the presence of these compounds are = 3. 20 +/- 0.21 microM/min, = 1.50 +/- 0.12 microM, = 200.2 +/- 8.1 microM/min, and = 100.2 +/- 8.2 microM. These values were compared to those obtained for the pair L-tyrosine/L-DOPA. The kinetic and structural reaction mechanisms of tyrosinase were corroborated for these physiological phenolic compounds.
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01-internacional
Base de dados:
MEDLINE
Assunto principal:
Agaricus
/
Monofenol Mono-Oxigenase
/
Agaricales
/
Glutamina
Idioma:
En
Revista:
J Agric Food Chem
Ano de publicação:
1999
Tipo de documento:
Article