好熱性糸状菌Thermoascus aurantiacusによるアミラーゼの生産とその酵素化学的諸性質

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A thermophilic fungus, Thermoascus aurantiacus IFO 31693,produced amylases extracellularly. For the production of amylases, the addition of 2 to 4% starch as a carbon source and of 0.5% sodium nitrate as a nitrogen source were effective. Two amylases were purified from the culture filtrate of the organism incubated in a 2% starch medium for 6 d at 40℃. One (amylase I-b) was obtained as a partially purified protein (M_r, about 75,000) and the other (amylase II) as an electrophoretically homogeneous protein (M_r, about 56,000). Amylases I-b and II were respectively identified as being exo-and endo-type enzymes, with optimum pHs for their activities of 5.0 and 4.5. The thermostability of amylase II was enhanced by calcium chloride, and the enzyme was stable when heated at 60℃ for 3h. The activity of amylase I-b was not affected by calcium chloride, but was gradually reduced by heating at 60℃. The optimum temperatures of amylases I-b and II were 65 and 70℃ (Ca^<2+>), respectively.
社団法人日本生物工学会の論文
1998-03-25