STUDIES ON THE PARTIALLY UNCOUPLED OXIDATION OF TETRAHYDROPTERINS BY PHENYLALANINE-HYDROXYLASE

被引：14

作者：

DAVIS, MD ^{[1
]}

KAUFMAN, S ^{[1
]}

机构：

[1] NIMH,NEUROCHEM LAB,BLDG 36,ROOM 3D30,BETHESDA,MD 20892

来源：

NEUROCHEMICAL RESEARCH | 1991年 / 16卷 / 07期

关键词：

TETRAHYDROBIOPTERIN; TETRAHYDROPTERIN; PHENYLALANINE; PHENYLALANINE HYDROXYLASE;

D O I：

10.1007/BF00965691

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

The uncoupled portion of the partially uncoupled oxidation of tetrahydropterins by phenylalanine hydroxylase can be described by the same model as we have recently derived for the fully uncoupled reaction (Davis, M.D. and Kaufman, S. (1989) J. Biol. Chem. 264, 8585-8596). Although essentially no hydrogen peroxide is formed during the fully coupled oxidation of tetrahydrobiopterin or 6-methyltetrahydropterin by phenylalanine hydroxylase when phenylalanine is the amino acid substrate, significant amounts of hydrogen peroxide are formed during the partially uncoupled oxidation of 6-methyltetrahydropterin when para-fluorophenylalanine or para-chlorophenylalanine are used in place of phenylalanine. Similarly, during the partially uncoupled oxidation of the unsubstituted pterin, tetrahydropterin, even in the presence of phenylalanine, hydrogen peroxide formation is detected. The 4a-carbinolamine tetrahydropterin intermediate has been observed during the fully uncoupled tyrosine-dependent oxidations of tetrahydropterin and 6-methyltetrahydropterin by lysolecithin-activated phenylalanine hydroxylase, suggesting that this species is also a common intermediate for uncoupled oxidations by this enzyme.

引用

页码：813 / 819

页数：7

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