Reaction: xylitol + NAD+ = D-xylose + NADH + H+
Other name(s): XYL1 (gene name) (ambiguous)
Systematic name: xylitol:NAD+ oxidoreductase
Comments: Xylose reductases catalyse the reduction of xylose to xylitol, the initial reaction in the fungal D-xylose degradation pathway. Most of the enzymes exhibit a strict requirement for NADPH (cf. EC 1.1.1.431, D-xylose reductase (NADPH)). Some D-xylose reductases have dual coenzyme specificity, though they still prefer NADPH to NADH (cf. EC 1.1.1.307, D-xylose reductase [NAD(P)H]). The enzyme from Candida parapsilosis is a rare example of a xylose reductase that significantly prefers NADH, with Km and Vmax values for NADH being 10-fold lower and 10-fold higher, respectively, than for NADPH.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Lee, J.K., Koo, B.S. and Kim, S.Y. Cloning and characterization of the xyl1 gene, encoding an NADH-preferring xylose reductase from Candida parapsilosis, and its functional expression in Candida tropicalis. Appl. Environ. Microbiol. 69 (2003) 6179-6188. [PMID: 14532079]