Chisty, Md. Ay Az Hasan
(2005)
Partial Protease Characterization, In Vitro Protein
Digestibility And Utilization Of Dietary Soybean In Giant
Freshwater Prawn, Macrobrachium Rosenbergii (De Man).
PhD thesis, Perpustakaan Hamzah Sendut.
Abstract
Biochemical assays and electrophoretical observations using SDS-PAGE was
conducted for partial identification and characterization of proteases in the digestive
system of giant freshwater prawn (Macrobrachium rosenbergii). pH optima of the crude
enzyme extracts of prawn showed 3 peaks in activity at pH 3.0, 6.0 and 9.0. The acid
proteinase and trypsin at pH 2.5 and 9.0 showed higher activity respectively at 3 and
5hrs after the last feeding. Presence of serine class proteinase was identified using
PMSF that reduced 33% of the total proteolytic activity. Reduction in activity by 82%
and 55% using specific inhibitors TLCK and TPCK confirmed the presence of trypsin
and chymotrypsin respectively while EDTA reduced 34% activity resembles the
presence of metallo-proteinase. Characterization of the alkaline proteinases by 12%
SDS-PAGE, after incubation of extract with or without specific inhibitors, produced six
active bands of 13 to 136 kDa molar mass. Two trypsin bands of 13 and 36 kDa, three
chymotrypsin bands of 23, 47 and 73 kDa and one metallo-proteinase of 136 kDa were identified from zymogram. The results suggest that an acid protease responsible for the
initial digestion of proteins and trypsin and chymotrypsin are the main enzymes responsible for the rest.
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