温度对嗜冷酵母糖代谢途径某些关键酶的活性效应

EFFECT OF TEMPERATURE ON THE ACTIVITY OF SOME ENZYMES REPRESENTATIVE OF EMP PATHWAY AND TCA CYCLE IN PSYCHROPHILIC YEAST

对嗜冷酵母Y1 8和酿酒酵母细胞中EMP途径和TCA循环中一些关键酶的温度特性进行了比较研究。Y1 8细胞中 ,1 ,6 二磷酸果糖醛缩酶、琥珀酸脱氢酶和己糖激酶对温度很敏感 ,符合Feller提出的冷活性的概念属于冷活性酶类。柠檬酸合成酶的温度特性类似于中温酶。α 酮戊二酸脱氢酶存在不同温度特性的同功酶。通过对嗜冷酵母和中温酶母细胞中琥珀酸脱氢酶的Km 值进行比较 ,结果显示嗜冷酵母琥珀酸脱氢酶在 2 0℃具有较低的Km值。另外还对嗜冷菌细胞中代谢酶类的一些特点进行了讨论。

Some key enzymes of EMP pathway and TCA cycle in a psychrophilic yeast Y18 were studied in this paper compared with those of \%Saccharomyces cerevisiae. \%The results indicated that fructose 1,6\|bisphosphate aldolase, succinate dehydrogenase, and hexokinase in Y18 were very thermolabile and have high activity at low temperature. These enzymes belong to cold\|active enzymes. Alpha\|ketoglutarate dehydrogenase existed possiblly in isoenzyme which had different temperature characteristics. Citrayl synthetase was very similar in temperature characteristics to that of mesophiles. The \%K\%\-m value of succinate dehydrogenase both from Y18 and \%S.cerevisiae\% were studied and Some features of enzyme in psychrophiles were also discussed in this paper.