Partial purification and properties of thermostable intracellular amylases from a thermophilic Bacillus sp. AK-2.
Intracellular thermostable amylases from a thermophilic Baccilus sp. AK-2 have been isolated and purified. The crude enzyme, having pH optimum at 6.5. and temperature optimum at 68 degrees C was purified by DEAE-cellulose column chromatography. Three separable enzyme fractions having starch hydrolyzing property were eluted by lowering the pH from 8.5 to 7.0. Electrophoretic mobility of these fractions showed a single band. Calcium ion up to a concentration of 20 mM had an activating effect on the three fractions. The optimum temperature for the three fractions (FI, FII and FIII) was 65 degrees C and the pH optimum for each was 6.0, 6.5 and 6.0, respectively. The -SH group in the amylase molecule was essential for enzyme activity. Except for Ca2+, Mg2+, Sr2+ and Mn2+ all other metal ions studied inhibited both alpha and beta-amylase activities. EDTA showed dose dependent non-competitive inhibition. Product formation studies proved FI and FIII to be of the alpha-amylase type and FII of the beta-amylase type. The Km for the substrate (starch) in the presence or absence of EDTA was 0.8 X 10(-3) and 1.13 X 10(-3) g/ml for alpha-amylase and beta-amylase, respectively.
D000681:Amylases / Q000302:isolation & purification / Q000378:metabolism*; D001407:Bacillus / Q000201:enzymology*; D004492:Edetic Acid / Q000494:pharmacology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000302:isolation & purification; D008670:Metals / Q000494:pharmacology; D012988:Soil Microbiology; D000516:alpha-Amylases / Q000378:metabolism; D001614:beta-Amylase / Q000378:metabolism
D007527:Isoenzymes; D008670:Metals; D004492:Edetic Acid; D000681:Amylases; D000516:alpha-Amylases; D001614:beta-Amylase