The nature of enzyme action / by W.M. Bayliss.

  • Bayliss, William Maddock, Sir, 1860-1924.
Date:
1908
Catalogue details

Licence: In copyright

Credit: The nature of enzyme action / by W.M. Bayliss. Source: Wellcome Collection.

    86/112 (page 70)
    removed by precipitation with acetic acid and proteins with uranyl- acetate ; this last precipitate carried down with it, in a state 'of ad- sorption, the pepsinogen. By extracting the mass with a large amount of dilute sodium carbonate the greater part of the zymogen passed into solution again. The process of uranyl-acetate precipitation and extraction of precipitate with dilute sodium carbonate was repeated and the final extracts concentrated at 40°. The body so obtained gave only two of the protein reactions and these very faintly, namely, a fine precipitate with mercuric salts and with phosphotungstic acid. It must therefore be of non-protein nature, and, if so, the pepsin formed from it by the action of acid can scarcely be a protein. The physical properties of the substance are interesting. It was found to be slightly la;vo-rotatory. We have already seen reason to suppose that enzymes are optically active. It is adsorbed by kieselguhr, alumina and fibrin, but not by starch or sand. These facts serve to con- firm the view of the .specific nature of adsorption, since it can scarcely be held that pepsinogen has a greater chemical affinity for kieselguhr than it has for sand, although it would be expected to have more “affinity” for fibrin than for starch. It is of interest to notice the close similarity between the enzyme and its zymogen, at all events in the present case. As Glaessner re- marks, the conversion by very dilute mineral acids with such smooth- ness, rapidity and completeness is only explicable on the assumption of a very simple chemical process.