抄録
It is generally recognized that most of snake venoms manifest proteolytic activity (Zeller, 1951) . Several reports have recently been accumulated (Deutsch et al., 1955; Rao et al., 1956; Hadidian, 1956; Henriques et al., 1958; Maeno et al., 1958) to suggest the presence of more than one proteolytic enzymes in certain snake venoms.
Up to date, comparatively numerous informations have been available on the pharmacological function of the potent proteolytic enzymes of the Crotalidae venoms. Hemorrhage and necrosis are claimed to be attributable, at least in part, to the action of proteolytic enzymes (Houssay, 1930; Kellaway, 1939; Zeller, 1948; Porges, 1953; van Heyningen, 1954; Slotta, 1955; Kaiser et al., 1958; Maeno et al., 1958) . In our recent studies (Ohsaka et al., 1960, 1961) it was reported that zone electrophoretical fractionation, coupled by a new quantitative method for estimating hemorrhagic activity (Kondo et at., 1960), of Habu venom revealed the presence of at least two hemorrhagic principles, both of which were associated with proteolytic activity on casein. Eagle (1937) and Jánszky (1950) demonstrated a parallelism between the proteolytic activity of venoms and their blood coagulating activity. The proteolytic enzymes may also contribute to the hypotensive action of snake venom, resulting in shock, through damage given to vascular endothelium with consequent escape of blood from circulation (Kellaway, 1939; Porges, 1953) or through the liberation of bradykinin from serum globulin (Rocha e Silva et al., 1949; Prado et at., 1950) .
In view of the pharmacological function of proteolytic enzymes of Crotalidae venoms above-cited, and of the fact that such venoms also manifest lethal toxicity, it becomes of obvious interest and significance to know whether or not proteolytic activity in Habu snake venom can contribute to its lethal toxicity.
The experiments here reported indicate that at least the main part of lethal toxicity and of proteolytic activity on casein were independent of each other. Evidences suggesting the presence of several proteolytic enzymes in this venom will also be presented.
