M. Cereia et al., Glucoamylase activity from the thermophilic fungus Scytalidium thermophilum. Biochemical and regulatory properties, J BASIC MIC, 40(2), 2000, pp. 83-92
A glucoamylase activity produced by the thermophilic fungus Scytalidium the
rmophilum was purified 6.8-fold by ion exchange chromatography. The protein
exhibited a molecular mass of about 86 kDa (7% PAGE and SDS-PAGE), or 68.5
kDa (Bio Sil SEC-400 FPLC). The pi of the enzyme was 8.4. Optima of pH and
temperature, with starch or maltose as substrates were, 6.5/60 degrees C a
nd 5.0/55 degrees C, respectively. The enzyme had a half-life of 22 min at
55 degrees C with starch as substrate, and it was fully stable with maltose
. Maltase activity was activated by 10 mM Ba++ (7.8%); Mn++ (12.4%) or Mg+ (28%). The enzyme contained approximately 25.5% carbohydrate. K-m and V-ma
x values for starch and maltose were 0.28 mg/ml, 67.2 U/mg protein and 1.40
mg/ml, 5.61 U/mg protein, respectively. The products of hydrolysis of star
ch, detected by thin layer chromatography, showed only glucose after 30 min
, indicating a glucoamylase activity. The amino terminal sequence of the pu
rified protein showed 93% homology with a glucoamylase activity purified fr
om Humicola grisea var, thermoidea.