Abstract:

One of the key problems affecting the ethanol production from cellulose is the unbalanced redox between xylose reductase （XR） and xylitol dehydrogenase （XDH） in the xylose metabolic process. In this paper, some key amino acids that affect the activity or coenzyme specificity of XR are identified based on the database sources by using the bioinformatic methods such as the homology modeling and the molecular docking. The results indicate that （1） amino acids Lys21, Va1222, Glu223, Phe236 and Thr273 in Pichia stipitis XR have hydrogen bonding with nicotinamide adenine dinucleotide phosphate （NADP）, while amino acids Va1222, Glu223, Phe236, Glu237 and Thr273 have hydrogen bonding with nicotinamide adenine dinucleotide （NAD） ; （2） the mutagenesis of Lys21 （conserved） is likely to result in the binding of Pichia stipitis XR with NAD only, while that of Glu237 （ not conserved） is likely to result in the binding with NADP only; （3） unconserved amino acids Asn278 and Arg282 in Candida tropicalis XR have hydrogen bonding with NADP; and （4） the mutagenesis of Ash278 or/and Arg282 is likely to result in the unbinding of Candida tropicalis XR from NADP.

Key words: xylose reductase, site-directed mutagenesis, homology modeling, molecular docking, coenzyme bioinformation