Partial characterization of the digestive enzymes of Pacific bluefin tuna <Emphasis Type="Italic">Thunnus orientalis</Emphasis> under culture conditions |
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Authors: | Ana Matus de la Parra Antonio Rosas Juan Pablo Lazo Maria Teresa Viana |
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Institution: | (1) Departamento de Ecología y Biología Animal, Facultad de Ciencias, Universidad de Vigo, 36310 Vigo, Pontevedra, Spain;(2) Programa de Maestría y Doctorado en Oceanografía Costera, Facultad de Ciencias Marinas, Universidad Autónoma de Baja California (UABC), Ensenada, BC, Mexico;(3) Centro de Investigaciones Científicas de Educación Superior de Ensenada (CICESE), Km 107 carretera Tij-Eda, 22860 Ensenada, BC, Mexico;(4) Instituto de Investigaciones Oceanológicas, Universidad Autónoma de Baja California, Km 107 carretera Tij-Eda, 22860 Ensenada, BC, Mexico |
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Abstract: | The digestive enzyme activities of Pacific bluefin tuna Thunnus orientalis were evaluated for specific activity and characterized for pH and temperature optima in crude extracts of stomach, caecal
mass, and proximal, middle and distal intestine. A higher level of alkaline proteolytic activity was detected in the caecal
mass than in the proximal intestine. Total alkaline proteases, trypsin, chymotrypsin and leucine aminopeptidase (LAP) were
tested. The temperature and pH analyses showed that proteolytic activity as well as lipase were maximal in the alkaline range,
with a maximum at pH 9.0 and at temperatures between 35 and 60°C, except for the pepsin, which showed maximum activity at
the same temperatures but in the acid range (pH 3.0). The α-amylase activity showed a broader range in activity, both for
pH and temperature, with higher activity over the alkaline pH values and higher temperature. The lipase activity seems to
be nondependent on bile salts under our assay conditions, resulting in a significant activity reduction in the presence of
bile salts. This knowledge will allow the development of a gastrointestinal model (everted intestine) where food or feed will
be hydrolysed with the fish’s own enzymes, a project that is being undertaken in our laboratory as a contribution to the development
of novel diets for tuna fish. |
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Keywords: | Bile salts Digestive enzymes Pacific bluefin tuna Pancreatic lipase Thunnus orientalis |
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