RELATION OF PROPERTIES OF ISOLATED MYOSIN TO THOSE OF INTACT MUSCLES OF CAT AND SLOTH
RELATION OF PROPERTIES OF ISOLATED MYOSIN TO THOSE OF INTACT MUSCLES OF CAT AND SLOTH
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DOI：
10.1111/j.1432-1033.1967.tb00120.x
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发表时间：
1967-01-01
期刊：
影响因子：
--
通讯作者：
GOFFART, M
中科院分区：
文献类型：
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作者：
BARANY, M;CONOVER, TE;GOFFART, M
从猫和二趾树懒的趾长伸肌、腓肠肌内侧和外侧肌、胫骨前肌、前肢爪屈肌和膈肌制备肌球蛋白。肌动蛋白激活的，Ca ~（2+）激活的，EDTA激活的ATP酶活性的肌球蛋白从猫的肌肉是2至4倍高的肌球蛋白从相同的肌肉的树懒。在5.5至10.0的pH范围内，以及在50 mM至500 mM的KCl浓度范围内，在pH 7.0的Ca 2+激活的ATP酶活性的差异。两种肌球蛋白的动力学特征表明，树懒肌球蛋白ATP酶活性的Km和Vmax均比猫肌球蛋白低几倍。重组猫肌动球蛋白超沉淀的速度比树懒肌动球蛋白快4至6倍。当ATP浓度和肌球蛋白与肌动蛋白的比例改变时，这种超沉淀的差异没有明显变化。猫和树懒的肌动球蛋白的ATP酶活性和超沉淀速度之间的相关性。猫和树懒的各种肌肉的收缩时间被发现是成反比的肌动蛋白激活ATP酶活性的各自的肌球蛋白。横膈膜肌肉缩短的速度常数似乎与肌球蛋白的肌动蛋白激活的ATP酶活性成正比。肌球蛋白的ATP酶活性随收缩速度的不同而不同，而猫和树懒的肌球蛋白的肌动蛋白结合能力也相同。分离肌球蛋白的这些性质与猫和树懒肌肉的类似张力输出有关。
Myosin was prepared from the extensor digi-torum longus, gastrocnemius medialis and lateralis, tibialis anterior, flexor of the claws of the anterior limb, and diaphragm muscles of the cat and didactyl sloth (Choloepus hoffmanni Peters). Actin-activated, Ca2+-activated, and EDTA-activated ATPase activities of the myosins from cat muscles were 2 to 4 times higher than those of the myosins from the same muscles of the sloth. The difference in the Ca2+-activated ATPase activity was found in the pH range of 5.5 to 10.0, and in the KCl concentration range of 50 mM to 500 mM at pH 7.0. The kinetic characteristics of the 2 myosins indicated that both the Km and the Vmax of the ATPase activities of the sloth myosin were lower than those of cat myosin by a factor of several-fold. Reconstituted cat actomyosin superprecipitated 4 to 6 times faster than sloth actomyosin. This difference in the superprecipita-tion did not vary appreciably when the concentration of ATP and the ratio of myosin to actin were varied. A correlation between the ATPase activity and the speed of superprecipitation of actomyosins of the cat and sloth was shown. The contraction time of various muscles of the cat and sloth was found to be inversely proportional to the actin-activated ATPase activity of their respective myosins. The speed constant of shortening of the muscles of the diaphragm appeared to be proportional to the actin-activated ATPase activity of their myosin. In contrast to the ATPase activity of myosin, which varied according to the speed of contraction, the actin-binding ability of myosins of the cat and sloth was also the same. These properties of the isolated myosins were related to the similar tension output of the muscles of the cat and sloth.