evolution
the enzyme belongs to the AKR superfamily, monomeric (alpha/beta) 8-barrel proteins which bind NAD(P)(H) to metabolize an array of substrates
malfunction
compared to the wild-type, the knockout mutation of the endogenous 2,5DKR gene results in lower degradation of estradiol and methyltestosterone but has no effct on degradation of estrone and testosterone. Cell growth on ethanol, oestrone, estradiol, testosterone or methyltestosterone is reduced in the mutant strain compared to the wild-type
metabolism
2,5-DKG reductase catalyses the stereospecific reduction of 2,5-diketo-D-gluconic acid (2,5-DKG) at position C-5 to 2-keto-L-gulonic acid (2-KLG), a key intermediate in the production of L-ascorbic acid
metabolism
the enzyme reduces 2,5-didehydro-D-gluconate, a key step in the microbial synthesis of vitamin C
more
three consensus sequences of the AKR superfamily are found as GxxxxDxAxxY, LxxxGxxxPxxGxG and LxxxxxxxxxDxxxxH. GxxxxDxAxxY is the active site, LxxxGxxxPxxGxG is the cofactor-binding site for NAD(P)(H), and LxxxxxxxxxDxxxxH is required for supporting the 3D structure
physiological function
the enzyme catalyses the reduction of 2,5-diketo-D-gluconic acid to 2-keto-L-gulonic acid, a direct precursor (lactone) of L-ascorbic acid (vitamin C). This reaction is an essential step in the biocatalytic production of the food supplement vitamin C from D-glucose or D-gluconic acid
