Effect of growth conditions on cofactor-linked xylose reductase activity in Pachysolen tannophilus
1989
VanCauwenberge, J.E. | Bolen, P.L. | McCracken, D.A. | Bothast, R.J.
Xylose reductase (E.C.1.1.1.21) is the enzyme responsible for conversion of xylose to xylitol in the fermentation of pentoses to ethanol by the yeast P. tannophilus. Cell-free extracts from anaerobically grown cells yield two forms of xylose reductase. One form requires either NADPH or NADH as a cofactor and has an isoelectric point (pI) of 5.1. A second form requires only NADPH as a cafactor and has a pI of 6.4 Cell-free extracts from aerobically grown cells also yielded two reductase forms, but the NADPH-active form predominated. Both forms have a molecular weight of 36,000 daltons. These two forms exhibiting xylose reductase activity may exist as two separate proteins or possibly as a single protein that undergoes modification.
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