A.—Proteolytic Action.
The proteolytic action of venoms on gelatine, fibrin, and egg-albumen has been studied by Flexner and Noguchi,[53] Delezenne,[54] and subsequently by Noc[55] in my laboratory. It was already known that in vivo certain venoms exert a manifestly dissolving action on the endothelium of blood-vessels and on the muscular tissues themselves.
Delezenne, on his part, has established the existence in snake-venoms of a kinase analogous to the kinase of leucocytes and enterokinase. Venom alone does not attack egg-albumen coagulated by heat, but it confers an exceedingly strong digestive power on inert pancreatic juices.
Lachesis-venom has been found to be much the richest in kinase. It digests gelatine perfectly, and when this substance has been subjected to its action it is no longer capable of being solidified.
Lannoy,[56] on the other hand, experimenting upon albuminoid substances (casein, albumins of ox-serum) in solution, has shown that Cobra-venom and that of Vipera disintegrate the albuminoid molecule; but the latter remains soluble after the addition of formol and is no longer precipitable by acetic acid. The hydrolysis never leads to the stage of peptone, but only to the formation of albumoses which give biuret-reaction.
The action of venoms upon fibrin may be demonstrated in vitro by bringing sufficient quantities of venom, 1 centigramme, for example, into contact with small fragments of non-heated fibrin, derived from blood clots from an ox, rabbit, or birds, and carefully washed. These fragments soon separate from each other, and become dissolved in a space of time which varies according to the venom used. The Viperine-venoms, especially those of Lachesis and Ancistrodon, are the most active. Viper-venom is much less so, and the venoms of Colubridæ are the slowest.
This proteolytic action of the various venoms corresponds pretty exactly to their coagulant and decoagulant action on rabbit- or horse-plasma, so that, as I have already stated, we must suppose that the property possessed by Viperine-venoms of more or less rapidly dissolving blood which they have caused to coagulate, results from the fact that these venoms contain, in addition to a coagulant substance, another substance which is strongly proteolytic.
The latter is destroyed by heating. Lachesis-venom, when heated to 70° C., no longer has any dissolving action on either gelatine or fibrin. Moreover, antivenomous serum furnished by horses vaccinated against heated venoms does not prevent proteolysis by non-heated venoms. On the other hand, the serum of animals vaccinated against Viperine-venoms, simply filtered by the Chamberland process and non-heated, affords perfect protection to gelatine and fibrin against the dissolving action of these venoms.