Reaction catalyzed by (R,R)-butanediol dehydrogenase (1.1.1.4)
+
2
NADPH
+
2
=
+
+
2
NADP+
acetoin
+
2 NADPH
+
2 H+
=
(2R,3R)-2,3-butanediol
+
meso-2,3-butanediol
+
2 NADP+