根霉植酸酶的分离纯化和酶学性质研究

Purification and characteristics of the phytase from Rhizopus sp.

根霉（Ｒｈｉｚｏｐｕｓｓｐ．）ＭＲ０２０菌株所产胞外植酸酶，经硫酸铵分级沉淀、ＳｅｐｈａｄｅｘＧ－１００凝胶过滤和ＤＥＡＥ－ｃｅｌｕｌｏｓｅ离子交换层析，获得了２种植酸酶同工酶，其相对分子质量分别为３４０００和４００００，等电点分别为３．４８和３．８５。二者作用的最适温度均为５５℃；最适ｐＨ分别为２．６和４．６。Ｃａ２＋、Ｆｅ２＋和Ｍｇ２＋对酶有激活作用。

Two isoenzymes of phytase from Rhizopus sp. MR020 were purified by ammonium sulfate precipitation, gel filtration chromatography and DEAE cellulose chromatography. Their moleculer weight are 34 000 and 40 000; isoelectric point are 3.48 and 3.85; and optimal pH are 2.6 and 4.6, respectively. The optimal temperature for them is 55 ℃, and activity can be activated by Ca 2+ , Fe 2+ , Mg 2+ , inhibited by Cu 2+ and NBS 2+ .