Einfluß der Reaktion auf die Eiweiß verdauende Kraft des Papains.

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Abstract
Maximum activities of papain upon fibrin were at ph 2.5, as with pepsin, and at pn 11, as with trypsin. A maximum activity on fibrin at pn 11 was also found in the gastric juice of Astacus fluviatilis. A smaller maximum was found at pH 4.5, which was also observed with the action upon proteins and albumoses where formol titration was used. Moreover a maximum of the action on fibrin appeared at ph 7, when phosphate was present. The attempts to isolate a pepsin- or trypsin-like enzyme from the original latex failed, but a preparation was obtained, soluble in water, which has a stronger peptic and tryptic action upon fibrin than the original one. It behaves, however, quite differently from a mixture of the purest pepsin and trypsin preparations. The activating influence of NaCN on the action of papain both on fibrin and serum proteins or albumoses is not noticeable at stronger acid reactions, but increases with increasing pn'', at pH 11 the action on fibrin is powerfully activated. It is assumed that it is not the very weak HCN, which is hardly dissociated at an acid or even neutral reaction, but rather the CN ions which have an activating influence. The suggestion is made that in papain a single enzyme may exist, and that all the peculiarities during the digestion of proteins depend on the condition of this enzyme or of the substrate.

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