桑蚕卵中酯酶A_4的研究

Studies on the esterase A4 of the eggs of Bombyx mori L..

取产后两天内25℃保存的桑蚕卵为材料,精制酯酶A_4。将滞育卵中精制的酶液置5℃下冷藏,冷藏初期酶活性极低,大致在12～13日达最大值。以后迅速降低,体外保存的温度条件与酯酶A_4活性有关,较高的保存温度能促使酶活性峰提早出现:而低温保护能延缓酶的活化进程。酯酶A_4精制过程中,通过Sephadex G-25凝胶过滤,将大部分物质分段与酶分离排除,在5℃条件下,酶活性峰出现以前的任何时候加入排除分段物质,都可以停止酶的活性化,只有当重新除去所加的排除分段物质时,酶的活性化进程才得以继续。

The esterase A4 has been purified from diapause eggs of Bombyx mori 2 days after oviposition. This enzyme activity remained at low levels during the early period of chilling at 5℃ in vitro. It suddenly increased on the 12th day of chilling and reached its peak on the 13th day, then it was followed by a sudden fall. Incubation temperature in vitro had some bearing on the enzyme activation. Most parts were seperated from esterase A4 as void fraction through sephadex G-25 gel filtration. The esterase A4 activity elevation could be stopped under 5℃ by adding such kind of void fraction before the peak of enzyme showed. The esterase A4 activation could resume only when the void fraction was excluded.