Anti-S2 peptides and antibodies bind cooperatively to the myosin dimer with high affinity and stabilize the unfolded state of S2

Abstract

Fluorescently labeled synthetic peptides (stabilizer and destabilizer) and antibodies (MF20, MF30, polyclonal), that target myosin subfragment-2 (S2) or light meromyosin (LMM), bound myosin, and all but polycolonal antibody caused a statistically significant change in the anisotropy. Their binding to myosin S2/LMM was confirmed when they labeled the A-band of the sarcomere in expansion microscopy images of rabbit skeletal myofibrils. The variations in the anisotropy readings depended on the mass that is small for the synthetic peptides, and large for the antibody and myosin.