Enzymological characteristics of pepsinogens and pepsins purified from lizardfish (Saurida micropectoralis) stomach.

One major pepsinogen, PG-I, and two minor pepsinogens, PG-II and PG-III were purified from lizardfish stomach by ammonium sulfate precipitation and two chromatographic columns. The three purified PGs migrated as single bands in native-PAGE gels with molecular weights (MW) ranging from 36 to 38 kDa. Each PG was converted to pepsin (P) at pH 2.0, and the MW were determined as 32 kDa (for P-I), 31 kDa (for P-II) and 30 kDa (for P-III). The optimum pH and temperature of pepsins were 2.0-3.5, and 40-50 °C. All 3 pepsins were strongly inhibited by pepstatin A. Divalent cations slightly stimulated the pepsin activities, but ATP had no effect on the pepsins. Purified pepsins were effective in the hydrolysis of various proteins. K and k of the three pepsins for hemoglobin hydrolysis were 107.64-276.61 µM and 18.30-32.68 s, respectively. The new pepsins have potential for use in protein food procession and modification.