多聚半乳糖醛酸酶及其化学修饰酶的酶学性质

摘要

探明多聚半乳糖醛酸酶特别是其化学修饰酶的酶学性质,以期发现比天然酶酶学性质更佳的酶.该研究以水溶性低分子量壳寡糖作为修饰剂对已纯化的多聚半乳糖醛酸酶(PG)进行化学修饰,得到化学修饰酶(COS·PG),然后分析PG和COS-PG的酶学性质如酶比活力、最适pH、最适温度、pH稳定性、温度稳定性等.结果显示:修饰后,化学修饰酶(COS-PG)的酶比活力和糖含量大幅度提高,与天然酶(PG)相比,修饰酶的酶比活力提高了153.42%,糖含量提高了43.11%,氨基修饰率为32.85%,酶活力回收率为126.51%;修饰后,COS-PG的最适pH由修饰前的4.0变为4.0～4.6,最适温度由修饰前的50～55℃变为55～60℃,pH稳定性、温度稳定性均有较大提高.表明COS-PG的酶比活力、最适pH、最适温度、pH稳定性、温度稳定性均明显优于PG.%To find out the enzymatic charateristics of polygalacturonase (PG) and its chemically modified enzyme, the enzyme specific activities, optimal pH and temperature, as well as stabilities of pH and temperature of PG and chitosan oligosaccharide modified enzyme, COS-PG were investigated. Compared with PG, the activity of modified enzyme ( COS-PG) was increased by 153％, and polycarbohydrate content was increased by 43.11％. Its amino modification rate was 32. 85％, and enzyme activity recovery was 126.51％. The optimal pH value and temperature of COS-PG also increased,being 4.0-4.6 and 55-60 C, respectively. Meanwhile, the stabilities of pH and temperature were improved as well. In a word, the characters of COS-PG were better than those of PG.