【摘要】 从Rhizopus microsporus var.chinensis CICIM F0088菌株中分离纯化一种新的具有生淀粉降解能力的糖化酶,并研究其酶学性质.经硫酸铵沉淀、双水相交换、DEAE-650M阴离子层析、Bio-Rad制备电泳等步骤后获得电泳均一的糖化酶,其相对分子质量约为52×103.该酶最适反应pH为4.5,在pH3.5～6.5范围内稳定;最适反应温度为75℃,具有较宽的pH耐受范围和较高的温度耐受性.经飞行质谱分析得到酶蛋白中3个肽段的氨基酸序列,通过比对发现,该酶与NCBI中已报道的糖化酶序列具有一定的同源性.更多还原

【Abstract】 A novel raw starch digesting glucoamylase from Rhizopus microsporus var.chinensis was purified by sequential ammonium sulfate precipitation,aqueous two-phase systems (ATPS),DEAE-650M chromatography and Bio-Rad Prep Cell.The protein performed a ralative molecular mass of 52×103 estimated by SDS-PAGE.The purified glucoamylase behaved the maximum activity at pH 4.5 and was stable between pH 3.5 to 6.5.Furthermore,the enzyme exhibited the maximum activity at 75 ℃.The amino acid sequences of three peptides from the purified enzyme were analyzed by LTQ (Liquid chromatographyion trap mass spectrometry),and those peptides compared with that of reported glucoamylase amino acid sequence in NCBI was similar in some extent.更多还原