在微摩尔浓度的钙离子存在下，法安明可诱导肌动球蛋白丝的张力降低。
Fragmin induces tension reduction of actomyosin threads in the presence of micromolar levels of Ca2+.
作者信息
Sugino H, Matsumura F
出版信息
J Cell Biol. 1983 Jan;96(1):199-203. doi: 10.1083/jcb.96.1.199.
Fragmin was able to reduce the isometric tension of Physarum actomyosin threads to 15-30% of the control tension at the Ca2+ concentrations greater than 10(-6) M. However, fragmin had no effect on the tension of threads when the Ca2+ concentration was lowered below 10(-7) M. The tension once reduced by fragmin could not be recovered by the removal of Ca2+. The remaining tension was shown to be still active from the experiment with quick release or stretch of the thread. This tension reduction is parallel to the decrease in viscosity of F-actin solution by fragmin. Electron microscopy showed that F-actin filaments became shorter in the thread after the tension was reduced by fragmin. Therefore, the severing of F-actin by fragmin in micromolar concentration of calcium resulted in the relaxation of tension by actomyosin threads.
在钙离子浓度高于10⁻⁶ M时，抑肽酶能够将绒泡菌肌动球蛋白丝的等长张力降低至对照张力的15% - 30%。然而，当钙离子浓度降至10⁻⁷ M以下时，抑肽酶对丝的张力没有影响。一旦被抑肽酶降低的张力，不会因去除钙离子而恢复。通过对丝进行快速释放或拉伸的实验表明，剩余的张力仍然是活跃的。这种张力降低与抑肽酶使F - 肌动蛋白溶液粘度降低是平行的。电子显微镜显示，在张力被抑肽酶降低后，丝中的F - 肌动蛋白丝变短。因此，在微摩尔浓度的钙存在下，抑肽酶切断F - 肌动蛋白导致肌动球蛋白丝的张力松弛。
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