Effect of NaCl on the heating activation of the heat-stable alkaline proteinases from various animal muscles.

1. Heat-stable alkaline proteinase (HAP) showed a wide distribution in fish, avian and mammalian muscles, while the total activity varied among animal species. 2. Total activity of HAP was changeable according to the degree of maturation in the case of chum salmon. 3. Effect of NaCl on HAPs varied among animal species. 4. It seems likely that the different sensitivity of HAPs to NaCl reflects the difference in the living circumstances of each animal species. 5. It is also postulated that the different sensitivity of HAPs to NaCl reflects the conformational diversity of the regulatory structure of HAP among animal species.