Hey-Ferguson A, Elbein A D
J Bacteriol. 1970 Mar;101(3):777-80. doi: 10.1128/jb.101.3.777-780.1970.
An enzyme, d-mannose ketol isomerase, catalyzing the isomerization of d-mannose and d-fructose was purified approximately 60-fold from cells of Mycobacterium smegmatis grown on mannose as the sole carbon source. This enzyme was shown to catalyze the conversion of d-mannose and d-lyxose to ketoses. The ketose produced from mannose was identified as fructose by chemical and chromatographic methods. The reaction was shown to be reversible, the equilibrium ratio of fructose to mannose being approximately 65 to 35. The pH optimum was about 7.5, and the K(m) for mannose was estimated to be 7 x 10(-3)m. Mannose isomerase activity was greatest in cells grown on mannose, whereas cells grown on fructose had about 30% as much activity. Very low levels of activity were detected in cells grown on other substrates. There was an immediate increase in enzyme activity on transfer of cells from nutrient broth to a mannose mineral salts medium.
一种催化D-甘露糖和D-果糖异构化的酶——D-甘露糖酮醇异构酶，从以甘露糖作为唯一碳源生长的耻垢分枝杆菌细胞中纯化出来，纯化倍数约为60倍。该酶被证明能催化D-甘露糖和D-来苏糖转化为酮糖。通过化学和色谱方法鉴定出由甘露糖产生的酮糖为果糖。该反应被证明是可逆的，果糖与甘露糖的平衡比约为65比35。最适pH约为7.5，甘露糖的米氏常数（K(m)）估计为7×10⁻³m。甘露糖异构酶活性在以甘露糖生长的细胞中最高，而以果糖生长的细胞活性约为前者的30%。在以其他底物生长的细胞中检测到的活性水平非常低。当细胞从营养肉汤转移到甘露糖矿物盐培养基时，酶活性立即增加。
