This enzyme is present in some but not all Rhizobium species and belongs in the GFO/IDH/MocA protein family [2]. This enzyme differs from hepatic 1,5-anhydro-D-fructose reductase, which yields 1,5-anhydro-D-glucitol as the product (see EC 1.1.1.263). In Sinorhizobium morelense, the product of the reaction, 1,5-anhydro-D-mannitol, can be further metabolized to D-mannose [1]. The enzyme also reduces 1,5-anhydro-D-erythro-hexo-2,3-diulose and 2-ketoaldoses (called osones), such as D-glucosone (D-arabino-hexos-2-ulose) and 6-deoxy-D-glucosone. It does not reduce common aldoses and ketoses, or non-sugar aldehydes and ketones [1].
