RIBONUCLEOTIDE REDUCTASE - A RADICAL ENZYME
RIBONUCLEOTIDE REDUCTASE - A RADICAL ENZYME
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DOI：
10.1126/science.6306767
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发表时间：
1983-01-01
期刊：
影响因子：
56.9
通讯作者：
EHRENBERG, A
中科院分区：
文献类型：
--
作者：
REICHARD, P;EHRENBERG, A
核糖核苷酸还原酶催化脱氧核糖核苷酸的酶促形成，这是DNA合成的必要步骤。来自大肠杆菌或哺乳动物的天然形式的酶含有其多肽结构的一部分，由铁中心稳定的游离酪氨酸自由基。在核糖C-2羟基被H原子取代的催化过程中，自由基参与了所有可能性。第二种，无活性形式的大肠杆菌还原酶缺乏酪氨酸基。大肠杆菌的提取物含有两种形式相互转化的活性。酪氨酸自由基是在O2存在的情况下引入的，而厌氧有利于其去除，这表明在O2的DNA合成中起调节作用。
Ribonucleotide reductases catalyze the enzymatic formation of deoxyribonucleotides, an obligatory step in DNA synthesis. The native form of the enzyme from Escherichia coli or from mammalian sources contains as part of its polypeptide structure a free tyrosyl radical, stabilized by an Fe center. The radical participates in all probability in the catalytic process during the substitution of the hydroxyl group at C-2 of ribose by a H atom. A second, inactive form of the E. coli reductase lacks the tyrosyl radical. Extracts from E. coli contain activities that interconvert the 2 forms. The tyrosyl radical is introduced in the presence of O2, while anaerobiosis favors its removal, suggesting a regulatory role in DNA synthesis for O2.