Purification and characterization of pepsinogens and pepsins from the stomach of rice field eel (<Emphasis Type="Italic">Monopterus albus</Emphasis> Zuiew) |
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Authors: | Wu-Yin Weng Tao Wu Wei-Qin Chen Guang-Ming Liu Kiyoshi Osatomi Wen-Jin Su Min-Jie Cao |
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Institution: | (1) College of Biological Engineering, The Key Laboratory of Science and Technology for Aquaculture and Food Safety, Jimei University, 361021 Jimei, Xiamen, China;(2) Faculty of Fisheries, Nagasaki University, Nagasaki 852-8521, Japan; |
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Abstract: | Three pepsinogens (PG1, PG2, and PG3) were highly purified from the stomach of freshwater fish rice field eel (Monopterus
albus Zuiew) by ammonium sulfate fractionation and chromatographies on DEAE-Sephacel, Sephacryl S-200 HR. The molecular masses
of the three purified PGs were all estimated as 36 kDa using SDS–PAGE. Two-dimensional gel electrophoresis (2D-PAGE) showed
that pI values of the three PGs were 5.1, 4.8, and 4.6, respectively. All the PGs converted into corresponding pepsins quickly at
pH 2.0, and their activities could be specifically inhibited by aspartic proteinase inhibitor pepstatin A. Optimum pH and
temperature of the enzymes for hydrolyzing hemoglobin were 3.0–3.5 and 40–45°C. The K
m values of them were 1.2 × 10−4 M, 8.7 × 10−5 M, and 6.9 × 10−5 M, respectively. The turnover numbers (k
cat) of them were 23.2, 24.0, and 42.6 s−1. Purified pepsins were effective in the degradation of fish muscular proteins, suggesting their digestive functions physiologically. |
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