Department of Agricultural Chemistry, Kyoto University, Sakyo-ku, Kyoto 606, Japan.
Appl Environ Microbiol. 1987 Mar;53(3):519-22. doi: 10.1128/aem.53.3.519-522.1987.
Washed cells of Rhodococcus erythropolis IFO 12540 were found to convert only the l-(+)-isomer of pantoyl lactone to the d-(-)-isomer in a racemic mixture of pantoyl lactone. Under suitable reaction conditions, the amount of d-(-)-pantoyl lactone synthesized was 18.2 mg/ml (94.4% enantiomer excess; molar yield, 90.5%). This conversion was suggested to proceed through the following successive reactions: first, the enzymatic oxidation of l-(+)-pantoyl lactone to ketopantoyl lactone; second, the rapid and spontaneous hydrolysis of the ketopantoyl lactone to ketopantoic acid; and then, the enzymatic reduction of the ketopantoic acid to d-(-)-pantoic acid. After the reaction d-(-)-pantoic acid could be lactonized by means of acid treatment. During the conversion, the d-(-)-isomer, which was initially present in the reaction mixture, did not undergo any modification.
红平红球菌IFO12540 的洗涤细胞被发现仅在泛酰内酯的外消旋混合物中将 l-(+)-泛酰内酯转化为 d-(-)-对映异构体。在合适的反应条件下，合成的 d-(-)-泛酰内酯的量为 18.2mg/ml（94.4%对映体过量；摩尔产率，90.5%）。这种转化被认为是通过以下连续反应进行的：首先，l-(+)-泛酰内酯的酶促氧化为酮泛酰内酯；其次，酮泛酰内酯迅速自发水解为酮戊二酸；然后，酮戊二酸的酶促还原为 d-(-)-戊二酸。反应后，d-(-)-戊二酸可以通过酸处理内酯化。在转化过程中，最初存在于反应混合物中的 d-(-)-异构体没有发生任何变化。
