Wondrack L M, Hsu C A, Abbott M T
J Biol Chem. 1978 Sep 25;253(18):6511-5.
Cell-free preparations from Rhodotorula glutinis catalyzed the conversion of deoxyribonucleosides to ribonucleosides in a pyrimidine deoxyribonucleoside 2' -hydroxylase reaction. The reaction occurred with only thymidine or deoxyuridine, of the common deoxyribonucleosides, without detachment of the deoxyribose moiety, at the nucleoside level. The same enzyme preparations catalyzed the conversion of thymine to 5-hydroxymethyluracil in a thymine 7-hydroxylase reaction. Requirements for molecular oxygen, alpha-ketoglutarate, Fe2+, and ascorbate indicated that the 2' -hydroxylase and 7-hydroxylase reactions are of the alpha-keto-acid dioxygenases class. The requirements for alpha-ketoglutarate and Fe2+ were very stringent. During the course of the 2' -hydroxylase and 7-hydroxylase reactions, alpha-ketoglutarate was decarboxylated to form succinate and CO2 so that the ratio of hydroxylated nucleoside or pyrimidine to CO2 was 1:1.5-Hydroxymethyluracil and 5-formyluracil also stimulated the decarboxylation of alpha-ketoglutarate and thus appeared to undergo 7-hydroxylase reactions.
粘红酵母的无细胞制剂在嘧啶脱氧核糖核苷2'-羟化酶反应中催化脱氧核糖核苷转化为核糖核苷。在核苷水平上，该反应仅在常见的脱氧核糖核苷中的胸苷或脱氧尿苷发生，且脱氧核糖部分未脱离。相同的酶制剂在胸腺嘧啶7-羟化酶反应中催化胸腺嘧啶转化为5-羟甲基尿嘧啶。对分子氧、α-酮戊二酸、Fe2+和抗坏血酸的需求表明，2'-羟化酶和7-羟化酶反应属于α-酮酸双加氧酶类。对α-酮戊二酸和Fe2+的需求非常严格。在2'-羟化酶和7-羟化酶反应过程中，α-酮戊二酸脱羧形成琥珀酸和CO2，因此羟化核苷或嘧啶与CO2的比例为1:1。5-羟甲基尿嘧啶和5-甲酰基尿嘧啶也刺激α-酮戊二酸的脱羧，因此似乎也经历7-羟化酶反应。
