Thermostable glucose-tolerant glucoamylase produced by the thermophilic fungus Scytalidium thermophilum.
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.
Aquino
A C
AC
Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14.040-901 Ribeirão Preto, São Paulo, Brasil.
Jorge
J A
JA
Terenzi
H F
HF
Polizeli
M L
ML
D001203:Ascomycota / Q000201:enzymology* / Q000254:growth & development; D003470:Culture Media; D004795:Enzyme Stability; D005087:Glucan 1,4-alpha-Glucosidase / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D007700:Kinetics; D013379:Substrate Specificity
D003470:Culture Media; D005087:Glucan 1,4-alpha-Glucosidase; D005947:Glucose