【摘要】 首次从家蚕（Bombyx mori L.）蛹体脂肪织织及真皮细胞分离得到催化丫-L-谷氨酰-2-L-氨基丁酸反应生成吡咯烷酮羧酸和2-L-氨基丁酸的Y-谷氨酰环化转移酶。并采用硫酸铵沉淀、葡聚糖G-75柱层析、DEAE-纤维素DE₃₂柱层析和羟基磷灰石柱层析等步骤,将该酶提纯了1,285倍。高度纯化后的酶,对Y-L-谷氨酰-2-L-氨基丁酸具有最适pH7.2-7.4,最适酶反应温度为47℃,米氏常数（Km）为0.04M。在分离纯化过程中未发现蚕体内有该酶的同功酶存在,纯化后的酶溶解于pH8.0、0.01M的Tris—HCl缓冲掖中,-30℃经过一个月没有发现明显的失活现象,但在4℃中一个月后丧失活性76％。更多还原

【Abstract】 A r-glutamylcyclotransferase which catalyzes the conversion of r-L-glutamyl-2-L-aminobutyric acid into free pyrrolidone carboxyic acid and free aminobutyric acid has been isolated from pupae of the silkworm, Bombyx mori.The enzyme was purified 1285-fold by (NH4)2SO4 fractionation and chromatography on Sephadex G-75, DEAE-cellulose and hydroxylapatite. The purified enzyme has a pH optimum of 7.2 - 7.4, a T optimum of 47t. a Km of 0.04M toward Y-L-glutamyl-2-L-aminobutyic acid. The isozyme of Y’glutamyl cyclotransferase has not been found in the silkworm. The purified enzyme coulol be stored at -301C in O.OlM Tris-HC1 buffer, pH 8.0 for at least one month -without significant loss of activity. At 4X). however, more than 76% of the activity was lost within 30 days.更多还原