| Summary: | 碩士 === 國立臺灣大學 === 農業化學系 === 85 === In this study, we isolate and screen a salt-tolerant koji
mold from soil. After identification, we name it as Aspergillus
tamarii NTU-FC-M1. The crude enzyme solution made from koji
shows the highest protease activityat 55℃and it has fair
thermal stability under 45℃. Besides, it still remains 30% of
protease activity in 18% of sodium chloride. After
purification steps of ultrafiltration (MWCO 10,000), 30-70%
acetone precipitation and DEAE-Sepharose CL-6B chromatography,
we get the purified alkaline protease. The alkaline protease
is a serine protease. Its optimal pH is between 10-11and its
optimal temperature is 55℃. It loses about 50% of activity
under 45℃for 1 hour. And it remains 13% of activity in 18% of
sodium chloride. The molecular weight of the alkaline protease
is estimated as about 30,000Da by gelfiltration or 37,600Da by
SDS-PAGE.
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