Functional characterization of an aldose reductase (bmALD1) obtained from the silkworm Bombyx mori

We describe a new member of the aldo-keto reductase (AKR) superfamily in the silkworm Bombyx mori. On the basis of its amino acid sequence and phylogenetic tree, this AKR belongs to the AKR1B family and has been designated as bmALD1. In the current study, recombinant bmALD1 was overexpressed, purified to homogeneity and kinetically characterized. We discovered that bmALD1 uses NADPH as a coenzyme to reduce carbonyl compounds such as DL-glyceraldehyde, glucose and 2-nonenal. No NADH-dependent activity was detected. To the best of our knowledge, bmALD1 is only the third AKR characterized in silkworm which, given its substrate specificity, could play a major role in glucose metabolism and antioxidant reactions. Our data provide an increased understanding of insect AKR function.