摘要
采用硫酸铵分级、DEAE-纤维素离子交换层析、Sephadex G-150凝胶过滤等方法,从黑曲霉AS3.4309变异株B-11的发酵液中分离出三种电泳均一的糖化酶(GⅠ、GⅢ、GⅡ)。其收率分别为0.8%、50%和18.6%。GⅠ、GⅢ和GⅡ的分子量分别为27000、67000和53000;等电点分别为3.38、3.52和3.59;含糖量分别为8.7%、13.6%和18.3%;最适pH分别为4.4、4.6和4.6;对可溶性淀粉的K_m值分别为2.0、0.77和1.18g/L;二级结构中α-螺旋含量分别为18.4%、23.9%和28.9%;最适温度均为70℃。生淀粉可吸附GⅢ,吸附率达80%。此外还测定了三种同工酶的氨基酸组成及含量。GⅠ、GⅡ和GⅢ均由一条多肽链组成。
Three isoenzymes of glucoamylases, GⅠ, GⅡ, and GⅢ, were isolated from fermentation broth of the mutant Aspergillus niger AS 3.4309 by using ammonium sulfate fraction DEAE-cellulose column chromatography and Sephadex G-150 gel filtration. The yields of GⅠ, GⅢ and GⅡ were 0.8%, 50%, and 18.6% respectively.The molecular weights of GⅠ, GⅢ, and GⅡ were 27000, 67000 and 53000, respectively, and they all consist of single polypeptide chain; their isoelectric points were 3.38, 3.52 and 3.59; the K_m values for soluble starch were 2.0, 0.77 and 1.18 g/L; the optimum pH were 4.4, 4.6 and 4,6, respectively; the optimum temperatures were all 70℃. GⅢ can be adsorbed by raw starch with adsorption yield of 80%.In addition, amino acid compositions of the 3 isoenzymes and their CD spectra were determined.
出处
《微生物学报》
CAS
CSCD
北大核心
1991年第3期213-220,共8页
Acta Microbiologica Sinica
关键词
黑曲霉
糖化酶
Aspergillus niger
Glucoamylase isoenzymes
