酱油曲中谷氨酰胺酶酶学特性研究

Research on the Enzymatic Properties of Glutaminase in Soy Sauce Koji

以酱油曲中的谷氨酰胺酶为研究对象,通过蒸氨法测定谷氨酰胺酶酶活力,探究不同温度、pH、NaCl浓度对谷氨酰胺酶酶活力和稳定性的影响,同时分析了谷氨酰胺酶底物专一性和底物浓度对其的抑制作用。研究结果表明,酱油曲中谷氨酰胺酶最适温度为55℃,在此温度下维持8 h,酶活力损失70%以上,酶热稳定性较差;最适pH为7.0,在pH 6.0~9.0范围内均能维持较高的酶活力,pH稳定性优于温度;NaCl对谷氨酰胺酶酶活力具有较强抑制作用,6%NaCl浓度条件下维持4 h,酶活力完全被抑制。同时,谷氨酰胺酶也能够水解天冬酰胺,并且高浓度谷氨酸对酶活力没有明显的抑制作用。该研究结果可为酱油中谷氨酸研究提供理论指导。

Take glutaminase in soy sauce koji as the research object,the activity of glutaminase is determined by ammonia evaporation method,and the effects of different temperatures,pH values and NaCl concentration on the activity and stability of glutaminase are investigated,and the specificity and concentration of glutaminase substrate on its inhibition are also analyzed.The results show that the optimal temperature of glutaminase in soy sauce koji is 55℃,the enzyme activity loss rate is above 70%at 55℃for 8 h,and the enzyme thermal stability is lower.The optimal pH is 7.0,and the enzyme activity is higher within the range of pH 6~9,the stability under pH value is better than that under temperature.NaCl has a stronger inhibitory effect on the activity of glutaminase,and the enzyme activity is utterly inhibited under the conditions of 6%NaCl concentration for 4 h.Meanwhile,glutaminase can hydrolyze asparagine,the high-concentration glutamic acid has no apparent inhibitory effect on the enzyme activity.The results of this research can provide theoretical guidance for probing into the glutamic acid in soy sauce.