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Appl. Environ. Microbiol., 04 1995, 1580-1585, Vol 61, No. 4
A Kuhn, C van Zyl, A van Tonder and BA Prior
A cytosolic aldo-keto reductase was purified from Saccharomyces cerevisiae
ATCC 26602 to homogeneity by affinity chromatography, chromatofocusing, and
hydroxylapatite chromatography. The relative molecular weights of the
aldo-keto reductase as determined by sodium dodecyl sulfate-polyacrylamide
gel electrophoresis and size exclusion chromatography were 36,800 and
35,000, respectively, indicating that the enzyme is monomeric. Amino acid
composition and N-terminal sequence analysis revealed that the enzyme is
closely related to the aldose reductases of xylose-fermenting yeasts and
mammalian tissues. The enzyme was apparently immunologically unrelated to
the aldose reductases of other xylose-fermenting yeasts. The aldo-keto
reductase is NADPH specific and catalyzes the reduction of a variety of
aldehydes. The best substrate for the enzyme is the aromatic aldehyde p-
nitrobenzaldehyde (Km = 46 microM; kcat/Km = 52,100 s-1 M-1), whereas among
the aldoses, DL-glyceraldehyde was the preferred substrate (Km = 1.44 mM;
kcat/Km = 1,790 s-1 M-1). The enzyme failed to catalyze the reduction of
menadione and p-benzoquinone, substrates for carbonyl reductase. The enzyme
was inhibited only slightly by 2 mM sodium valproate and was activated by
pyridoxal 5'-phosphate. The optimum pH of the enzyme is 5. These data
indicate that the S. cerevisiae aldo- keto reductase is a monomeric
NADPH-specific reductase with strong similarities to the aldose reductases.
Copyright © 1995, American Society for Microbiology
Purification and partial characterization of an aldo-keto reductase from Saccharomyces cerevisiae
Department of Microbiology and Biochemistry, University of the Orange Free State, Bloemfontein, South Africa.
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