幽門垂Trypsin Inhibitorの研究-I

Abstract

The trypsin inhibitor has been obtained from the pyloric coeca of bonito. The method of isolation was essentially the same as used for pancreatic trypsin inhibitor1), the outlines of which are as follows. The minced pyloric coeca was extracted with 0.25 N-H2SO4 and ammonium sulfate was added to a concentration of 17% (W/W) to the extract. The resulting precipitate (Fr. 1) was filtered off, and ammonium sulfate was added further to a concentration of 38% to the supernatant. The formed precipitate (Fr. 2) was dissolved in distilled water, an equal volume of 5% trichloroacetic acid was added to the solution, and the mixture was heated at 80°C for 5 minutes. The precipitate was removed, and the active principle in the filtrate was precipitated by salting out with 38% ammonium sulfate. The precipitate was dissolved in distilled water at pH 3, and ammonium sulfate was added to a concentration of 20%. The formed precipitate (Fr. 4) was separated, then ammonium sulfate was added to 38% concentration in the supernatant. The aqueous solution of the precipitate (Fr. 5) was further fractionated by etheanol. The precipitate which formed with 80% ethanol concentration was designated as Fr. 6. The precipitate which formed from the supernatant with 90% ethanol concentration was designated as Fr. 7. Only Fr. 6 seemed to have a trypsin inhibiting activity (Table 1 to 3, and Fig. 1). The several properties of the matter were studied. The biuret, ninhydrin, xanthoproteic, Sakaguchi, and Adamkiewicz color reactions were positive. The ultraviolet absorption spectrum of the aqueous solution was typical of proteins or polypeptides (Fig 2). It was not dialyzed through cellophane membrane. The aqueous solution was very stable and remained unchanged even after being heated in boiling water bath for 15 minutes (Table 4 and Fig. 3). Therefore, it seemes to belong to polypeptide.