The dynamics of four regions of tropomyosin was assessed using saturation transfer electron paramagnetic resonance in the muscle fiber. In order to fully immobilize the spin probe on the surface of tropomyosin. a bi-functional spin label was attached to i. i+4 positions via cysteine mutagenesis. https://www.allfixelectricales.shop/product-category/timer-knob-ratchet/