Arabitol dehydrogenase

Fig. 5. Assimilation of D-xylose, L-arabinose and D-arabinose. In yeasts and fungi, pentoses are assimilated by way of oxidoreductases. D-xylose. L-arabinose and D-arabinose are each reduced to their respective polyols by aldose reductases, designated here as Xor, Lar and Dar. Both D-xylose and L-xylose are reduced to xylitol, which is symmetrical. D-xylose and L-arabinose are the forms normally found in nature. D- and L-arabitol dehydrogenases (Dad and Lad) form D- and L-xylulose, respectively. D- and L-Xylitol dehydrogenase (Dxd and Lxd) mediate the formation of D- and L-xylulose from xylitol...

Hallborn et al. [115] cloned a short-chain dehydrogenase gene from P. stipitis CBS 6054 that has its highest activity with D-arabinitol as substrate. The D-arabinitol dehydrogenase activity is not induced by xylose but it can use xylitol as a substrate. D-Ribulose is the final product for this enzyme. This enzyme is similar to an NAD+-dependent D-arabitol dehydrogenase cloned from Candida albicans [116]. 

Adachi O, Fujii Y, Ghaly MF, Toyama H, Shinagawa E, Matsushita K (2001) Membrane-bound quinoprotein D-arabitol dehydrogenase of Gluconobacter suboxydans IFO 3257 a versatile enzyme for the oxidative fermentation of various ketoses. Biosci Biotechnol Biochem 65 2755-2762... 

Different pathways are available in nature for metabolism of arabinose and xylose which are converted to xylulose 5-phosphate (intermediate com-poimd) to enter the pentose phosphate pathway as shown in Figure 10.5. In yeasts, xylose is first reduced by xylose reductase to xylitol, which in turn is oxidized to xylulose by xylitol dehydrogenase. In bacteria and some anaerobic fungi, xylose isomerase is responsible for direct conversion of xylose to xylulose. Xylulose is finally phosphorylated to xylulose-5-phos-phate by xylulokinase. In fungi, L-arabinose is reduced to L-arabitol (by arabinose reductase), L-xylulose (by arabitol dehydrogenase), xylitol (by L-xylulose reductase). Xylitol is finally converted to xylulose (by xylitol dehydrogenase), whose activity is also part of xylose utilization pathways. In bacteria, L-arabinose is converted to L-ribulose (by L-arabinose isomerase), L-ribulose-5-P (by L-ribulokinase) and finally D-xylulose-5-P (by L-ribulose-5-P 4-epimerase) (Bettiga et al., 2008). 

L-arabitol Dehydrogenase Deficiency. A link to the deficiency of this enzyme was recognized in 2002 in a 16 month old girl. Clinical presentations included delayed motor development, facial dysmorphism, palatoschizis and multiple skeletal abnormalities [34-35]. 

L-arabitol dehydrogenase deficiency Withdraw fruits to reduce polyol level... 

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