Radioassay for oxidation of tyrosine by tyrosinase using L-(ring-3H)tyrosine and L-(carboxyl-14C)tyrosine.
نویسندگان
چکیده
منابع مشابه
Effective 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 ...
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It has been known for several years that L-ascorbic acid has an important role in the oxidation of tyrosine, as shown by experiments both in viva and in vitro with guinea pigs (1, 2). Further in vitro experiments with normal guinea pigs presented proof of the ability of cell-free liver homogenates to oxidize tyrosine (3). Since liver homogenates from severely scorbutic animals were thought to c...
متن کاملThe oxidation of tyrosine-containin peptides by tyrosinase.
* This study was supported by a grant from the National Science Foundation. A preliminary report was given by Dr. Yasunobu at the Conference on Pigment Cell Biology, Houston, Texas, November 1957. t Present address, Department of Chemistry,. University of Hawaii. $ Senior Postdoctoral Fellow of the National Science Foundation at the Department of Chemistry, University of Cambridge. mumto minimu...
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A new enzymatic method for rapid direct measurement of serum tyrosine is described, based on the amperometric measurement of the rate of oxygen consumption when tyrosine is oxidized in the presence of the enzyme tyrosinase in a phosphate buffer (0.1 mol/liter, pH 7.4). A Beckman Glucose Analyzer with a Clark electrode is used for the measurement. The procedure does not require removal of serum ...
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...
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ژورنال
عنوان ژورنال: Chemical and Pharmaceutical Bulletin
سال: 1982
ISSN: 0009-2363,1347-5223
DOI: 10.1248/cpb.30.2094