A RADICAL APPROACH TO ENZYME CATALYSIS

被引:55
作者
MARSH, ENG [1 ]
机构
[1] CAMBRIDGE CTR MOLEC RECOGNIT, CAMBRIDGE CB2 1QW, ENGLAND
关键词
D O I
10.1002/bies.950170511
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
Free radicals are generally perceived as highly reactive species which are harmful to biological systems. There are, however, a number of enzymes that use carbon-based radicals to catalyse a variety of important and unusual reactions. The most prominent example is ribonucleotide reductase, an enzyme which is crucial for the synthesis of DNA. In general, radicals are used to remove hydrogen from unreactive positions in the substrate, and in this way the substrate is activated to undergo chemical transformations that would otherwise be difficult to achieve. Several different mechanisms have evolved which allow enzymes to generate and maintain radicals in increasingly aerobic enviroments. An unexpected finding is the existance of stable protein-based radicals, residing on a variety of amino-acid side chains, which serve to link the radical-generating and catalytic sites and to store the radical between turnovers.
引用
收藏
页码:431 / 441
页数:11
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