On Pure Pepsin

Action of Pepsin on Gelatin

Crystalline Pepsin

The decrease in protein nitrogen and in the activity of solutions of crystalline pepsin at pH 1.8 and 45 degrees C. has been determined. The decrease in activity, as measured with eleven different methods, is in exact proportion to the decrease of protein nitrogen of the solution. The measurements were continued until less than 5 per cent of the original protein remained. These results indicate...

Crystalline Pepsin Iii. Preparation of Active Crystalline Pepsin from Inactive Denatured Pepsin By

The results (1) of the experiments with crystalline pepsin isolated from crude pepsin preparations indicated that the material is a pure substance and that the proteolytic activity is a property of the protein molecule itself and is not due to the presence of a separate non-protein impurity. No indication of the presence of a more highly active nonprotein molecule was obtained in the solubility...

Fluorescence studies on the active sites of porcine pepsin and Rhizopus-pepsin.

Fluorescence studies on the interaction, with porcine pepsin, of oligopeptides bearing a mansyl (Mns, 6-(N-methylanilino)-2-naphthalenesulfonyl) or dansyl (Dns, 5-dimethylaminonaphthalene-1-sulfonyl) group at the NH2 or COOH terminus have provided further evidence showing that the probe group is drawn into the extended active site largely as a consequence of the specific binding of the peptide ...

Immunological Studies on Pepsin and Pepsinogen

1. Alkali (pH 7.6)-denatured pepsins from swine, cattle, and guinea pigs precipitate in swine pepsin antiserum. Similarly treated pepsins from the rabbit, chicken, and shark do not. 2. Pepsin antisera react with both pepsin and pepsinogen, but do not react with the serum proteins from the homologous species. 3. Pepsinogen antisera react with pepsinogen, but not with twice crystallized pepsin, n...