초록
<P><B>Abstract</B></P> <P>A panel of microorganisms was screened for selective reduction ability towards a racemic mixture of prochiral 2-amino-3-methyl-4-ketopentanoate (<I>rac</I>-AMKP). Several of the microorganisms tested produced greater than 0.5mM 4-hydroxyisoleucine (HIL) from <I>rac</I>-AMKP, and the stereoselectivity of HIL formation was found to depend on the taxonomic category to which the microorganism belonged. The enzymes responsible for the AMKP-reducing activity, <I>Ap</I>AR and <I>Fs</I>AR, were identified from two of these microorganisms, <I>Aureobasidium pullulans</I> NBRC 4466 and <I>Fusarium solani</I> TG-2, respectively. Three AMKP reducing enzymes, <I>Ap</I>AR, <I>Fs</I>AR, and the previously reported <I>Bt</I>HILDH, were reacted with <I>rac</I>-AMKP, and each enzyme selectively produced a specific composition of HIL stereoisomers. The enzymes appeared to have different characteristics in recognition of the stereostructure of the substrate AMKP and in control of the 4-hydroxyl group configuration in the HIL product.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>