ABSTRACT
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°C, 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°C for 90 min, while, they were completely inactivated when heated at 60°C 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 R[f] value corresponding to a molecular weight of 20,000 Da was observed with the enzyme extracted from Macaroni while two bands with R[f] 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