PEG修饰的辣根过氧化物酶及其在非水介质中的性质

酶的化学修饰可以明显提高酶在有机相中的活力。通过氧化过氧化物酶（ＨＲＰ）的糖链后引入氨基再连接甲氧基聚乙醇（ＰＥＧ）５０００和在酶的肽链上连接ＰＥＧ５０００，发现ＨＲＰ多肽链上修饰后的酶在水相中的活力几乎没有变化，但通过氧化糖链连接ＰＥＧ的酶在水相中的活力下降近２倍。在甲苯及二氧六环含量较高的体系中，修和均呈上升趋势。特别在甲苯体系中两种修饰酶活力都比未经修饰的酶提高了近２倍。稳定性研究表明，不论

PEG Modified Horseradish Peroxidase and Its Properties in Nonaqueous Media

Modification of enzymes can enhance their activities in organic solvents. Horseradish peroxidase(HRP) was modified with methoxy PEG 5000 which was linked onto HRP peptidal free aminos or onto the aminos introduced through the oxidation of sugar side chains of HRP. It was found the enzyme with PEG linked to peptide chain expressed a nearly same activity as the native HRP in aqueous system. However, PEG modified HRP by oxidation of carbohydrate chains remained only about one third activity of the native HRP. The same results were observed in reversed micelles and in dioxane of less than 30%. Apparently, both PEG modified HRP had the higher activities in high concentration of dioxane. Especially, the activities of the modified HRP in toluene were both enhanced up to nearly 3 fold. When HRP was modified with PEG through the amino groups of peptide chain, it was more stable than the native enzyme in water, dioxane and toluene. However, the stability of PEG modified HRP by carbohydrate chains was higher in water and lower in both dioxane and toluene in comparison with native HRP.