ADP DISSOCIATION FROM ACTOMYOSIN SUBFRAGMENT-1 IS SUFFICIENTLY SLOW TO LIMIT THE UNLOADED SHORTENING VELOCITY IN VERTEBRATE MUSCLE
ADP DISSOCIATION FROM ACTOMYOSIN SUBFRAGMENT-1 IS SUFFICIENTLY SLOW TO LIMIT THE UNLOADED SHORTENING VELOCITY IN VERTEBRATE MUSCLE
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DOI：
10.1073/pnas.82.3.658
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发表时间：
1985-01-01
影响因子：
11.1
通讯作者：
WHITE, HD
中科院分区：
文献类型：
--
作者：
SIEMANKOWSKI, RF;WISEMAN, MO;WHITE, HD
ADP从肌动球蛋白亚片段1 （S1）解离的速率常数在本实验室和其他地方测量了各种脊椎动物肌肉类型。在溶液中，ADP与肌动球蛋白- s1的分离限制了ATP对肌动球蛋白- s1 -ADP的分离速率，并且可能也限制了收缩肌肉的过桥脱离速率。对于ADP从肌动球蛋白- s1解离的速度足够慢的肌肉类型，可以使用停止流动的方法来测量，速率常数几乎与附着的十字桥解离的最小允许速率常数的理论值相同。ADP解离足够慢，是限制这些肌肉最大缩短速度的分子步骤。ADP解离速率常数随肌肉类型的变化可能是调节缩短速度的一般系统发育机制。
The rate constant for dissociation of ADP from actomyosin subfragment 1 (S1) was measured in this laboratory and elsewhere for a variety of vertebrate muscle types. The following observations were made: In solution, the dissociation of ADP from actomyosin-S1 limits the rate of dissociation of actomyosin-S1-ADP by ATP and, presumably, also limits the rate of crossbridge detachment in contracting muscle. For muscle types in which the rate of ADP dissociation from actomyosin-S1 is slow enough to measure using stopped-flow methods, the rate constants are nearly the same as the theoretical value for the minimum allowable rate constant for dissociation of an attached crossbridge. ADP dissociation is sufficiently slow to be the molecular step that limits the maximum shortening velocity of these muscles. Variation with muscle type of the rate constant for ADP dissociation may be a general phylogenetic mechanism for regulating shortening velocity.