Biochemical Characterization, Activity Comparison and Isoenzyme Analysis of Amylase and Alkaline Proteases in Seven Cyprinid Fishes

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Objective: The activity of digestive enzymes and isoenzyme patterns were characterized and comparatively studied in seven cyprinid fishes randomly collected from Kongkaew swamp, Khon Kaen province, Thailand.Materials and Methods: Fish samples compose of Osteochilus hasselti, Labiobarbus spilopleura, Puntius gonionotus, Osteochilus lini, Cyclocheilichthys repasson, Cyclocheilichthys apogon and Puntius brevis.Data were analyzed using one-way ANOVA.Results: Different fish species revealed different optimum temperatures and optimum pH values for amylase and alkaline protease activities.For the amylase activity, all species displayed optimum pH at 8.0, whereas the optimum pH values for alkaline proteases were observed in the range of 8.0-10.0depending on fish species.The optimum temperatures for both amylase and alkaline proteases of all fish species were 45-65EC.Both amylase and alkaline protease activities determined at optimum temperature and optimum pH were higher than enzyme activities determined at water temperature of the swamp.At the latter condition, alkaline proteases and amylase retained their activities about 8-42% and 14-32% of maximum activities determined at optimum conditions.Interestingly, Puntius brevis showed highest activities of both amylase and alkaline proteases.Determination of enzyme isoforms using native polyacrylamide gel electrophoresis and enzyme zymography revealed different isoform patterns in different fish species.The same fish species exhibited the same amount and the same molecular weight of enzyme isoforms, which were different from other fish species.Conclusion: Amylase and alkaline proteases from seven fish species revealed the different optimum pH and temperatures with the values in the ranges of pH 8.0-10.0 and 45-65EC.Different fish species displayed different patterns of enzyme isoforms.The unique pattern of enzyme isoform in each fish species is probably used for fish identification.

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