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用硫酸铵分部沉淀法提取菠萝植株茎中的菠萝蛋白酶,经Sephadex G-25、DEAE-cellulose 52离子交换柱层析、Native-PAGE纯化得到含多个等电点的菠萝蛋白酶。高pI的茎酶经裂解,醋酸薄膜电泳后,发现能够向负极移动的蛋白。氨基酸组成测定发现,茎菠萝蛋白酶为富含苯丙氨酸的蛋白。免疫印迹实验发现茎中提取的菠萝蛋白酶与菜心绿叶中发现的富含苯丙氨酸的碱性蛋白(PP)具有同源性。
Bromelain was isolated from the stems of pineapple by ammonium sulfate fractionation and purified by Native-PAGE using Sephadex G-25 and DEAE-cellulose 52 ion exchange chromatography to obtain bromelain with multiple isoelectric points. The high-pI stem enzyme was cleaved, and acetic acid thin-film electrophoresis revealed a protein that was able to migrate to the negative electrode. Amino acid composition determination found that stem bromelain is a phenylalanine-rich protein. Western blotting revealed that the bromelain extracted from the stem has homology with the phenylalanine-rich basic protein (PP) found in the green leaves of Brassica campestris.