RADIATION-INDUCED INACTIVATION OF FLAVOCYTOCHROME B(2) IN DILUTE AQUEOUS-SOLUTION

被引：7
作者：
BHATTACHARYA, D
SAHA, A
MANDAL, PC
机构：
[1] Nuclear Chemistry Division, Saha Institute of Nuclear Physics, Calcutta, 700 064
来源：
BIOCHIMICA ET BIOPHYSICA ACTA-PROTEIN STRUCTURE AND MOLECULAR ENZYMOLOGY | 1995年 / 1250卷 / 01期
关键词：
RADICAL SPECIES; MICHAELIS-MENTEN KINETICS; ENZYME INACTIVATION; FLAVOCYTOCHROME B(2); (SACCHAROMYCES-CEREVISIAE);
D O I：
10.1016/0167-4838(95)00040-2
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：
Effect of gamma radiation on flavocytochrome b(2) in dilute aqueous solution was studied. A study of the effect of the radiolytically produced inorganic free-radical anions such as I-2(-), BT2- and (SCN)(2)(.-) on the enzyme activity indicates the involvement of cysteine and tyrosine residues in the catalytic activity of flavocytochrome b(2). The changes in kinetic parameters, i.e., Michaelis-Menten constant K-m and maximal velocity V-max, due to irradiation under different conditions suggest that radiation induced enzyme inactivation is the result of destruction of active-site residues as well as modification of the substrate binding site. Fluorescence studies of unirradiated and irradiated enzyme reveal that FMN (flavin mononucleotide) is inaccessible to water radicals.
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页码：1 / 8
页数：8
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