维生素C二步发酵中L-山梨糖脱氢酶的性质及作用

PROPERTIES AND FUNCTIONS OF L-SORBOSE DEHYDROGENASE IN TWO-STEP FERMENTATION OF VITAMIN C

从氧化葡萄糖酸杆菌细胞质中分离纯化出L 山梨糖脱氢酶 (SDH) ,其分子量为 46× 10 3 ,表观分子量为 190× 10 3 ;在测试范围内 ,最适pH是 7.4,温度为 5 5℃ ,最稳定的 pH是 7.0 ,温度为 30℃以下 ;FeCl3 促进酶活 ,CoCl2 抑制酶活 .该酶活力与发酵产物 2 酮基 L 古龙酸的合成呈正相关 ;伴生菌促进产酸菌生长和代谢 ,并使该酶比活力增加 ,从而提高发酵系统中该酶的总活力 .图 11表 5参

L-sorbose dehydrogenase(SDH) was purified from the cell-free extract of Gluconobacter oxydans, ant its molecular weight is about 46×10 3 in the SDS-PAGE electrophoresis and apparent molecular weight is about 190×10 3. The correlation between the reaction rate of the purified enzyme and pH and temperature was calculated, which showed that optimum pH were 7.4 and temperature 55 ℃. The purified enzyme was fairly stable at around pH 7.0 and up to 30 ℃. FeCl 3 stimulated the enzyme activity, while CoCl 2 inhibited strongly. The activity of the enzyme is positively interrelated to the production of 2KGA in the fermentation. The accompanying strains promoted production of 2KGA in the fermentation by accelerating G. oxydans growth and metabolism and raising the special activity of SDH, which resulted in increases of the total activities of SDH in the fermentation system. Fig 11, Tab 5, Ref 9