SUMMARY—Natural actomyosin was prepared from the longissimus dorsi of both bovine and rabbit. Rabbit actomyosin had about two times the ATPase activity of bovine muscle actomyosin. However, both types of natural actomyosin behaved in a similar manner with respect to ionic conditions. They were activated by Mg++at low KCI (20–50 mM), inhibited by Mg++at high KCI (100 mM) and activated by Ca++at high KCI (100 mM). Bovine actomyosin, in contrast to rabbit actomyosin, did not show activation at low Mg++(0.01 mM) in the alkaline pH range. Maleate, when used as Tris‐Maleate buffer, inhibited superprecipitation of natural actomyosin from rabbit and bovine muscle. It was hypothesized that the low ATPase activity and the non‐activation at low Mg++in the alkaline pH range of bovine compared to rabbit actomyosin was a species dif
展开▼
