Aquino A C, Jorge J A, Terenzi H F, Polizeli M L
Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14.040-901 Ribeirão Preto, São Paulo, Brasil.
Folia Microbiol (Praha). 2001;46(1):11-6. doi: 10.1007/BF02825876.
Glucoamylase produced by Scytalidium thermophilum was purified 80-fold by DEAE-cellulose, ultrafiltration and CM-cellulose chromatography. The enzyme is a glycoprotein containing 9.8% saccharide, pI of 8.3 and molar mass of 75 kDa (SDS-PAGE) or 60 kDa (Sepharose 6B). Optima of pH and temperature with starch or maltose as substrates were 5.5/70 degrees C and 5.5/65 degrees C, respectively. The enzyme was stable for 1 h at 55 degrees C and for about 8 d at 4 degrees C, either at pH 7.0 or pH 5.5. Starch, amylopectin, glycogen, amylose and maltose were the substrates preferentially hydrolyzed. The activity was activated by 1 mmol/L Mg2+ (27%), Zn2+ (21%), Ba2+ (8%) and Mn2+ (5%). Km and vlim values for starch and maltose were 0.21 g/L, 62 U/mg protein and 3.9 g/L, 9.0 U/mg protein, respectively. Glucoamylase activity was only slightly inhibited by glucose up to a 1 mol/L concentration.
嗜热毁丝霉产生的葡糖淀粉酶经DEAE - 纤维素、超滤和CM - 纤维素色谱法纯化了80倍。该酶是一种糖蛋白，含糖量为9.8%，pI为8.3，摩尔质量为75 kDa（SDS - PAGE）或60 kDa（琼脂糖6B）。以淀粉或麦芽糖为底物时，pH和温度的最适值分别为5.5/70℃和5.5/65℃。该酶在55℃下稳定1小时，在4℃下，pH 7.0或pH 5.5时稳定约8天。淀粉、支链淀粉、糖原、直链淀粉和麦芽糖是优先被水解的底物。该活性被1 mmol/L Mg2+（27%）、Zn2+（21%）、Ba2+（8%）和Mn2+（5%）激活。淀粉和麦芽糖的Km和vlim值分别为0.21 g/L、62 U/mg蛋白质和3.9 g/L、9.0 U/mg蛋白质。在浓度高达1 mol/L时，葡萄糖对葡糖淀粉酶活性的抑制作用很轻微。
