アサリ桿晶体のアミラ-ゼの研究-1-分離精製とその性質〔英文〕

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An α-amylase was isolated from the crude extract of the crystalline-style of short-necked clam, Ruditapes philippinarum, by a combination of gel filtration on Sephadex G-50, Bio-Gel P-10, and Sephadex G-25 in the presence of strontium chloride. The specific activity was increased about 370-fold from the crude extract with high recovery. The enzyme was found to be homogeneous by polyacrylamide gel disc-electrophoresis. The enzyme gave an absorption spectrum which exhibited the maximum at 278nm and minimum at 250nm; the extinction coefficient, E1%1cm value at 280nm was 5.97. Optimum pH of the enzyme for soluble starch was found to be 6.2, and the maximum activity was found at 36°C on 20min incubation. The enzyme was relatively stable at pH values higher than 6.0, but was completely inactivated by heating at 55°C for 10min at pH 6.5. The enzyme was activated with chlorides of metals such as sodium, strontium, calcium, and magnesium; the highest activity was observed in the presence of 0.025M strontium chloride. The enzyme was protected from denaturation by strontium chloride when the enzyme was stored without freezing. But the enzyme was labile to freezing.
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