Purification and properties of d-xylulose reductase from Pachysolen tannophilus

Abstract

d-Xylulose reductase (EC 1.1.1.9) from Pachysolen tannophilus IFO 1007 was purified by Sephadex G-100 gel chromatography with three columns and DEAE cellulose chromatography. The purified enzyme was entirely homogeneous on disc gel electrophoresis. It was most active at pH 9.1–10.0 and 55°C, and stable at pH 7–9 and below 25 °C. Its activity was stimulated by NH 4Cl,NaCl,MgCl 2,KCl, glutathione, cysteine and glycine, and inhibited remarkably by SH inhibitor such as lead acetate, HgCl 2 and AgNO 3. It oxidized xylitol, sorbitol, ribitol and glycerine but not mannitol, inositol, arabitol and erythritol. Its K m values of enzyme against xylitol, sorbitol and ribitol were 1.1 × 10 −2 M, 3.0 × 10 −2 M and 5.0 × 10 −2 M, respectively. Its molecular weight was determined to be 120,000 by Sephadex G-200 column chromatography, and that of its subunit was 40,000 by sodium dodecyl sulfate polyacrylamide gel electrophoresis.