منابع مشابه
Tyrosinase reactivity in a model complex: an alternative hydroxylation mechanism.
The binuclear copper enzyme tyrosinase activates O2 to form a mu-eta2:eta2-peroxodicopper(II) complex, which oxidizes phenols to catechols. Here, a synthetic mu-eta2:eta2-peroxodicopper(II) complex, with an absorption spectrum similar to that of the enzymatic active oxidant, is reported to rapidly hydroxylate phenolates at -80 degrees C. Upon phenolate addition at extreme temperature in solutio...
متن کاملEffective L-Tyrosine Hydroxylation by Native and Immobilized Tyrosinase
Hydroxylation of L-tyrosine to 3,4-dihydroxyphenylalanine (L-DOPA) by immobilized tyrosinase in the presence of ascorbic acid (AH2), which reduces DOPA-quinone to L-DOPA, is characterized by low reaction yields that are mainly caused by the suicide inactivation of tyrosinase by L-DOPA and AH2. The main aim of this work was to compare processes with native and immobilized tyrosinase to identify ...
متن کاملIsotope effects in mechanistic studies of l-tyrosine halogen derivatives hydroxylation catalyzed by tyrosinase
The kinetic (KIE) and solvent (SIE) isotope effect methods were used to investigate the mechanism of enzymatic hydroxylation of halogenated derivatives of l-tyrosine to l-DOPA catalyzed by the enzyme tyrosinase (EC 1.14.18.1). The values of deuterium KIE and SIE were obtained using the non-competitive method with spectrophotometric measurements. The Lineweaver-Burk plots were used for determina...
متن کاملClxiii. Tyrosinase in Macrolepidoptera
THE work of a number of investigators has shown the presence of tyrosinase in various species of Macrolepidoptera, but it is not clear from the literature whether the occurrence of tyrosinase is exceptional or general. A survey has therefore been made of some widely representative species, comprising four Rhopalocera (butterflies) and 25 Heterocera (moths). Since most tyrosinase is usually foun...
متن کاملTyrosinase and Plant Respiration
The evidence presented in this paper supports the conclusion that at least 85 per cent of the oxygen uptake of the respiring tissue of potato tuber enters the chemistry of the cell by way of a tyrosinase-catalyzed oxidation. The qualitative aspects of this conclusion are in agreement with the claim made by Boswell and Whiting. However, the evidence offered by them in support of this conclusion ...
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ژورنال
عنوان ژورنال: Journal of Investigative Dermatology
سال: 1980
ISSN: 0022-202X
DOI: 10.1111/1523-1747.ep12535096