Dabrowska R, Goch A, Gałazkiewicz B, Osińska H
Biochim Biophys Acta. 1985 Sep 27;842(1):70-5. doi: 10.1016/0304-4165(85)90295-8.
Chicken gizzard caldesmon causes up to 40% inhibition of Mg2+-ATPase activity of rabbit skeletal muscle actomyosin. In the presence of chicken gizzard tropomyosin this inhibition is significantly increased, reaching a maximum (around 80%) at a molar ratio of caldesmon to actin monomer of 1 to 10-13. The inhibition of actomyosin ATPase takes place over a wide pH range (from 6.0 to 8.0) but is decreased with an increase in KCl and MgCl2 concentrations. Caldesmon, in the range of caldesmon/ actin ratios within which it inhibits actomyosin ATPase, forms bundles of parallelly aligned actin filaments. Calmodulin in the presence of Ca2+ dissociates these bundles and restrains the inhibition of actomyosin ATPase, provided that it is used at a high molar excess over caldesmon.
鸡胗钙调蛋白可使兔骨骼肌肌动球蛋白的Mg2+-ATP酶活性受到高达40%的抑制。在存在鸡胗原肌球蛋白的情况下，这种抑制作用显著增强，在钙调蛋白与肌动蛋白单体的摩尔比为1比10-13时达到最大值（约80%）。肌动球蛋白ATP酶的抑制作用在较宽的pH范围内（从6.0到8.0）发生，但随着KCl和MgCl2浓度的增加而降低。在抑制肌动球蛋白ATP酶的钙调蛋白/肌动蛋白比例范围内，钙调蛋白形成平行排列的肌动蛋白丝束。在存在Ca2+的情况下，钙调蛋白可使这些丝束解离，并抑制肌动球蛋白ATP酶的抑制作用，前提是其使用量大大超过钙调蛋白的摩尔过量。
