On Existence in Tissue Cell of Tryptase as a Second Intracellular Proteinase

1. Kidney, gastric mucosa or liver of rabbit has tryptase activity (hydrolysis of casein or gelatin) and its optimal reaction is near 7.8. Tryptic hydrolysis amounts are nearly constant with respect to each of these tissues throughout all the animals examined.2. Tryptase activity of liver or gastric mucosa is activated in the presence of dialyzed albumin solution.3. Tryptase activity of the gastric mucosa is found stronger than that of the liver, and ereptase activity (pepton, pH 7.8) is found stronger in the latter than in the former. Tryptase or ereptase activity of the kidney is, when compared with that of the gastric mucosa or those of the liver, exceedingly strong.4. By liver proteolysis, the hydrolysis of gelatin appears smaller than that of casein, and by gastric mucosa or by kidney proteolysis, the former is nearly equal to the latter.5. Hydrolysis of serum albumin or ovalbumin by these tissue homogenates at pH 7.8 is not recognizable.6. The above results are fairly consistent with those obtained with human gastric mucosa, and acceptance of the general existence in tissue cell of tryptase as a second intra-cellular proteinase other than catheptic proteinase is advocated. This work was carried out in part by a grant for development of scientific researches, given from the Ministry of Education. M. Hayakawa