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首页> 外文期刊>Biochimica et biophysica acta: BBA: International journal of biochemistry, biophysics and molecular biololgy. Proteins and Proteomics >Inorganic polyphosphate hydrolysis catalyzed by skeletal muscular actomyosin complexes is uncoupled with motility
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Inorganic polyphosphate hydrolysis catalyzed by skeletal muscular actomyosin complexes is uncoupled with motility

机译：通过骨骼肌肌动酶复合物催化催化的无机多磷酸盐水解与运动性脱模

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摘要

Hydrolysis of the triphosphate moiety of ATP, catalyzed by myosin, induces alterations in the affinity of the myosin heads for actin filaments via conformational changes, thereby causing motility of the actomyosin complexes. To elucidate the contribution of the triphosphate group attached to adenosine, we examined the enzymatic activity of heavy meromyosin (HMM) with actin filaments for inorganic tripolyphosphate (3PP) using a Malachite green method and evaluated using fluorescence microscopy the effects of 3PP on actin filament motility on HMM-coated glass slides. In the presence of MgCl2, HMM hydrolyzed 3PP at a maximum rate of 0.016 s(-1) HMM-1 which was four times lower than the hydrolysis rate of ATP. Tetrapolyphosphate (4PP) was hydrolyzed at a rate similar to that of 3PP hydrolysis. The hydrolysis rates of 3PP and 4PP were enhanced by roughly 10-fold in the presence of actin filaments. In motility assays, the presence of polyphosphates did not lead to the sliding movement of actin filaments. Moreover, in the presence of ATP at low concentrations, the sliding velocity of actin filaments decreased as the concentration of added polyphosphate increased, indicating a competitive binding of polyphosphate to myosin heads with ATP. These results suggested that the energy produced by standalone triphosphate hydrolysis did not induce the unidirectional motion of actomyosin and that the link between triphosphate and adenosine was crucial for motility.
机译：肌球蛋白催化的ATP的三磷酸三磷酸部分的水解诱导肌蛋白头通过构象变化的肌动蛋白长丝的亲和力的改变，从而引起肌动酶复合物的动力。为了阐明与腺苷附着的三磷酸基团的贡献，我们使用孔雀石绿色方法对肌动蛋白长丝（3pp）的肌动蛋白长丝进行了重量蛋白细丝的酶活性，并使用荧光显微镜评估了3pp对肌动蛋白长丝运动的影响在夹层涂层玻璃载玻片上。在MgCl 2存在下，以0.016 s（-1）HMM-1的最大速率水解3pp，其比ATP的水解速率低四倍。以类似于3pp水解的速率水解四聚磷酸（4pp）。在肌动蛋白长丝存在下，通过大约10倍提高3pp和4pp的水解速率。在动力测定中，多磷酸盐的存在不会导致肌动蛋白长丝的滑动运动。此外，在低浓度下的ATP存在下，随着添加的多磷酸盐的浓度增加，肌动蛋白长丝的滑动速度降低，表明用ATP对多磷酸盐对肌球蛋白头的竞争结合。这些结果表明，独立的三磷酸水解产生的能量没有诱导肌动素的单向运动，并且三磷酸和腺苷之间的联系对于运动性至关重要。

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