Dihydrofolate reductase from a methotrexate-resistant strain of Escherichia coli: dihydrofolate monooxygenase activity.
Dihydrofolate reductase from a methotrexate-resistant strain of Escherichia coli: dihydrofolate monooxygenase activity.
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来自甲氨蝶呤抗性大肠杆菌菌株的二氢叶酸还原酶：二氢叶酸单加氧酶活性。
DOI：
10.1016/0006-291x(73)90794-8
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发表时间：
1973
影响因子：
3.1
通讯作者：
Martin Poe
中科院分区：
文献类型：
--
作者：
Martin Poe
大肠杆菌MB1428菌株的二氢叶酸还原酶能催化二氢叶酸在C(9)N(10)键上的氧化裂解。反应产物之一经核磁共振氢谱鉴定为7，8-二氢蝶呤-6-甲醛。在25°、pH 7.2时，二氢叶酸的最大裂解速率为每分钟裂解0.05摩尔二氢叶酸，KM为17.5±2.5μM。甲氨蝶呤可完全抑制酶促反应。酶的作用机理被认为是二氢叶酸与酶结合时的明显“酸化”。叶酸经历了类似的酶氧化裂解，其周转数为0.0014，生成蝶呤-6-甲醛。甲氨蝶呤也被该酶缓慢降解。
Dihydrofolate reductase from strain MB 1428 ofEscherichia coliwas shown to catalyze the oxidative cleavage of dihydrofolate at the C(9)N(10) bond. One of the products of the reaction was identified as 7,8-dihydropterin-6-carboxaldehyde through its proton magnetic resonance spectrum. The maximal enzymatic rate was 0.05 moles dihydrofolate cleaved per minute per mole enzyme at 25° and pH 7.2, and the KMfor dihydrofolate was 17.5 ± 2.5 μM. The enzymatic reaction was fully inhibitable with methotrexate. The mechanism of enzyme action was proposed to be an apparent “acidification” of dihydrofolate upon binding to the enzyme. Folate underwent an analogous oxidative cleavage by enzyme with a turnover number of 0.0014, which produced pterin-6-carboxaldehyde. Methotrexate was also slowly degraded by the enzyme.