PhD Oral Defense: Novel chymotrypsins from Loligo opalescens and Sepioteuthis lessoniana: Isolation, Purification and Molecular Characterization

PhD Oral defense of Nana Akyaa Ackaah-Gyasi, Food Science and Agricultural Chemistry

Chymotrypsins are widely distributed among living species and have found widespread use in different industrial applications. However, until the last two decades, most studies on chymotrypsin have been restricted to mammalian species with few reported works on marine invertebrates.  The high catalytic activity of some aquatic enzymes at low temperatures, coupled with high pH and the relatively low thermal stability makes them robust in certain industrial applications where cold temperatures are preferred. In this study, chymotrypsin was purified to homogeneity and characterized from the viscera of two squid species (Loligo opalescens, cold water adapted and Sepioteuthis lessoniana, warm water adapted). Cold adapted chymotrypsin can transform substrates at low temperature thereby reducing loss of organoleptic properties and nutritional value of heat-sensitive substrates and products mostly found in industrial processing of food such as fish. They also provide economic benefit through energy savings during processing. This study also looks at the possibility of producing the enzymes using recombinant DNA technology, since it is currently not feasible or practical to extract these proteases from crude sources such as viscera for commercial application.

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