title: Purification and characterization of pepsinogens and pepsins from the stomach of rice field eel (Monopterus albus Zuiew).
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.
authors.affiliation: College of Biological Engineering, The Key Laboratory of Science and Technology for Aquaculture and Food Safety, Jimei University, 361021 Jimei, Xiamen, China.
authors.forename: Wu-Yin
authors.initials: WY
authors.lastname: Weng
authors.forename: Tao
authors.initials: T
authors.lastname: Wu
authors.forename: Wei-Qin
authors.initials: WQ
authors.lastname: Chen
authors.forename: Guang-Ming
authors.initials: GM
authors.lastname: Liu
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Osatomi
authors.forename: Wen-Jin
authors.initials: WJ
authors.lastname: Su
authors.forename: Min-Jie
authors.initials: MJ
authors.lastname: Cao
mesh_terms: D000818:Animals; D004524:Eels / Q000502:physiology*; D005753:Gastric Mucosa / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D010434:Pepsin A / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010435:Pepsinogens / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013696:Temperature
chemical_list: D010435:Pepsinogens; D010434:Pepsin A