8-Ketodeoxycoformycin and 8-ketocoformycin as intermediates in the biosynthesis of 2'-deoxycoformycin and coformycin.
8-Ketodeoxycoformycin and 8-ketocoformycin as intermediates in the biosynthesis of 2'-deoxycoformycin and coformycin.
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DOI：
10.1021/bi00415a059
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发表时间：
1988-07
期刊：
影响因子：
2.9
通讯作者：
J. Hanvey;E. Hawkins;D. Baker;R. Suhadolnik
中科院分区：
文献类型：
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作者：
J. Hanvey;E. Hawkins;D. Baker;R. Suhadolnik
已从链霉菌的无细胞提取物中分离出一种酶，其可催化8-酮脱氧共福霉素（8-KetodCF）和8-酮共福霉素（8-ketoCoF）分别还原为天然存在的核苷类似物2 '-脱氧共福霉素（dCF）和共福霉素（CoF）。部分纯化的还原酶需要NADPH作为辅因子，并立体特异性地将两种酮核苷底物的8-酮基还原为C-8处具有R构型的羟基。这是与从S分离的dCF和CoF的羟基相同的羟基构型。阿提库斯还原在核苷水平进行，不需要ATP。还原酶对NADPH辅因子具有立体特异性，因为它将pro-S而不是pro-R氢从NADPH的C-4转移到8-酮基。8-ketodCF和8-ketoCoF的表观Km分别为250和150 μ M。这些体外结果表明，8-ketodCF和8-ketoCoF可能是dCF和CoF生物合成的中间体，支持并扩展了我们早期的体内研究结果，该研究确定腺苷和D-核糖的C-1是dCF的碳-氮前体。一个可能的机制形成的DCF。
An enzyme has been isolated from cell-free extracts of Streptomyces antibioticus that can catalyze the reduction of 8-ketodeoxycoformycin (8-KetodCF) and 8-ketocoformycin (8-ketoCoF) to the naturally occurring nucleoside analogues 2'-deoxycoformycin (dCF) and coformycin (CoF), respectively. The partially purified reductase requires NADPH as the cofactor and stereospecifically reduces the 8-keto group of both ketonucleoside substrates to a hydroxyl group with the R configuration at C-8. This is the same configuration of the hydroxyl group as that of the dCF and CoF isolated from S. antibioticus. The reduction proceeds at the nucleoside level, and ATP is not required. The reductase is stereospecific for the NADPH cofactor in that it transfers the pro-S but not the pro-R hydrogen from C-4 of NADPH to the 8-keto group. The apparent Km for 8-ketodCF and 8-ketoCoF were 250 and 150 microM, respectively. These in vitro results, which show that 8-ketodCF and 8-ketoCoF may be intermediates in the biosynthesis of dCF and CoF, support and extend our earlier results from in vivo studies which established that adenosine and C-1 of D-ribose are the carbon-nitrogen precursors of dCF. A possible mechanism for the formation of dCF is presented.