‘赤霞珠’果实中2种己糖激酶同工酶部分酶学性质的研究

Studies on Partial Enzymatic Properties of Hexokinase Isozymes from 'Cabernet Sauvignon' Fruit

研究‘赤霞珠’果实中己糖激酶同工酶HXK1及HXK2的生化性质,以期为己糖激酶的研究提供基础数据。将前期RT-PCR及体外原核表达所得粗酶液用不同底物处理,紫外分光光度法测其动力学常数及最佳pH,双缩脲法测等电点。本实验表明,两种同工酶的米氏常数由大到小依次为果糖、甘露糖与葡萄糖,以葡萄糖为最佳反应底物。最大反应速度均在以果糖为底物的反应中出现。两种同工酶的等电点分别为5.8和5.6,最佳pH均为8.0左右。‘赤霞珠’同工酶HXK1及HXK2的生化性质符合己糖激酶的酶学特征。

This paper aimed to study the biochemical characteristics of two hexokinase（HXK） isozymes-HXK1 and HXK2 which derived from ＇Cabernet Sauvignon＇ fruits.Crude enzyme,which obtained from former experiment,was treated with different substrates,and the activity of hexokinase was characterized by changes of absorbance 340 nm.The pI of the enzyme was determined by biuret method.The results showed that the ascending Km values of different hexoses were fructose,mannose and glucose,which proved that glucose was the optimal substrate.The maximum reaction rate of both isozymes appeared in fructose reaction.The pI of HXK1 and HXK2 was 5.8 and 5.6,and the optimum pH of two isozymes was about 8.0.It was concluded that the biochemical properties of HXK1 and HXK2 corresponded with the characterization of HXK.