KINETIC-PROPERTIES OF LIGHT-DEPENDENT ASCORBIC-ACID OXIDATION BY MELANIN

被引：21

作者：

GLICKMAN, RD

SOWELL, R

LAM, KW

机构：

[1] Department of Ophthalmology, The University of Texas Health Science Center at San Antonio, San Antonio, TX

来源：

FREE RADICAL BIOLOGY AND MEDICINE | 1993年 / 15卷 / 04期

关键词：

ASCORBIC ACID; ISOASCORBIC ACID; MELANIN; LIGHT; KINETICS; FREE RADICALS;

D O I：

10.1016/0891-5849(93)90045-V

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 kinetic properties of ascorbic acid oxidation by light-activated melanin granules demonstrate the presence of a specific reactive site on the melanin granule saturable by ascorbic acid. Increased light intensity increased the V(max) and reduced the K(m) of this reaction, indicating increased affinity of the active site for ascorbic acid. The kinetics of this reaction are not markedly changed in a reduced-oxygen environment. Ascorbic acid oxidation is competitively inhibited by isoascorbic acid, an epimer of ascorbic acid, while other tested reducing agents are inactive. The K(i) for isoascorbic acid is 1 mM, about the same as the K(m) of ascorbic acid.

引用

页码：453 / 457

页数：5

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