壳聚糖-明胶共聚物的酶促合成及抑菌性质

Synthesis of Chitosan-Gelatin Copolymer in the Presence of MTGase and Its Bacteriostasis Properities

以纯化微生物转谷氨酰胺酶（MTGase）催化壳聚糖和明胶合成壳聚糖-明胶共聚物。经红外光谱测试表明，共聚物在MTGase催化下形成了席夫共价键。经DTA分析结果表明，共聚物是通过席夫键连接的。质量分数为1％的纯化共聚物溶液用溶菌酶于pH=5．0、50℃水解60min，水解液中还原糖浓度比水解前增加72．4％；用胰蛋白酶于pH=8．50、37℃水解60min，水解液中游离氨基浓度比水解前增加35．8％；由原子力显微镜观察到共聚物呈分枝状，分析结果表明，共聚物由壳聚糖和明胶组成。壳聚糖-明胶共聚物的均分子量为36．38KDa，等电点为8．43，在pH=5．0的稀HCl中的溶解度为8．7g/L；壳聚糖-明胶收率随明胶／壳聚糖的质量比增加而升高，但是其抑制金黄色葡萄糖球菌的效果随着二者的比例增加而降低。MTGase催化合成壳聚糖-明胶共聚物的最佳条件为：明胶／壳聚糖的质量比为0．6，pH=6．0、t=50℃、搅拌反应时间40min。平衡时共聚物的收率达到64．5％，其抑制金黄色葡萄糖球菌的效果仍保留70％。

Chitosan-Gelatin copolymer was synthesized with MTGase as catalyst from chitosan and gelatin. IR and DTA data indicated that chitosan and gelatin were linked via schiff bonds to yield the copolymer, the branched structure of which was confimed by AFM. The isoelectric point of the copolymer was 8.43, the average molelular mass was 36 - 38 KDa, and the solubility was 8.7 g/L in water at pH = 5.0. The yield increased with the ratio of gelatin to chitosan, and bacteriostasis of the copolymer to Staphylococcus aureus decreased. When the ratio was 0. 6, pH value was 6.0, temperature was 50 ℃, and reaction time was 40 min, the yield of the copolymer was 64.5%. Bacteriostasis to Staphylococcus aureus for 1% copolymer resolution was 70% that of chitosan.