Purification And Characterization Of Alkaline Proteases From The Viscera Of Mackerel (scumber Scumbrus) And Macaroni Fish (saurus Tumbil)

摘要

An alkaline protease was extracted from acetone powder prepared from the viscera of Mackerel (Scumber scumbrus) and Macaroni (Saurus tumbil) fish, precipitated from the extract by 40-60% ammonium sulfate, dialyzed and purified by gel exclusion chromatography. The optimal pH and optimal temperature of both enzymes were 8 and 50℃, respectively (using BAPNA as a substrate). Remarkable stability was observed at pH 6, where more than 75 % of the activity of both enzymes remained after 60 min while they retained more than 60% when incubated for the same period at pH 5.0. Furthermore, both enzymes retained more than 50% of their activity after heating at 50℃ for 90 min, while, they were completely inactivated when heated at 60℃ for 150 min. Gel exclusion chromatography increased the purification to 15.12 and 19.67-fold for Mackerel and Macaroni enzyme extracts, respectively. Only a single protein band with an Rf value corresponding to a molecular weight of 20,000 Da was observed with the enzyme extracted from Macaroni while two bands with Rf values close to 20,000 and 28,000 Da were noticed in the Mackerel extract when sodium dodecyl sulphate polyacrylamid gel electrophoresis (SDS-PAGE) was used for molecular weight determination.