Yamazaki S, Tsai L, Stadtman T C, Teshima T, Nakaji A, Shiba T
Proc Natl Acad Sci U S A. 1985 Mar;82(5):1364-6. doi: 10.1073/pnas.82.5.1364.
Reduction of 7,8-didemethyl-8-hydroxy-[5-2H]-5-deazariboflavin by the selenium-containing hydrogenase from Methanococcus vannielii gave a C-5 chirally labeled 1,5-dihydro derivative. The absolute configuration of the chiral label was shown to be (R) by comparison of the chemically degraded product with authentic samples of known absolute configurations. Therefore, the steric course of the enzymic reactions involving the 8-hydroxy-5-deazaflavin cofactor can be defined as follows: (a) reduction occurs on the si face of the 5-deazaflavin molecule; (b) oxidation proceeds by the abstraction of the pro-S hydrogen at C-5 of the 1,5-dihydro-5-deazaflavin. Thus, the selenium-containing hydrogenase and 8-hydroxy-5-deazaflavin-dependent NADP+ reductase from M. vannielii are si face specific.
来自万氏甲烷球菌的含硒氢化酶对7,8-二去甲基-8-羟基-[5-²H]-5-去氮核黄素的还原反应生成了一种C-5手性标记的1,5-二氢衍生物。通过将化学降解产物与已知绝对构型的真实样品进行比较，表明手性标记的绝对构型为(R)。因此，涉及8-羟基-5-去氮核黄素辅因子的酶促反应的立体化学过程可定义如下：(a) 还原发生在5-去氮核黄素分子的si面上；(b) 氧化是通过脱去1,5-二氢-5-去氮核黄素C-5位的前-S氢进行的。因此，来自万氏甲烷球菌的含硒氢化酶和8-羟基-5-去氮核黄素依赖的NADP⁺还原酶具有si面特异性。
