2'-Deoxy-ATP release myosin heads from the super relaxed state in permeabilized porcine myocardium

Abstract

The nucleotide 2-deoxy-ATP (dATP) is a naturally occurring energy substrate for myosin that enhances cross-bridge binding and cycling kinetics. In relaxed rodent cardiac and skeletal muscle, dATP repositions myosin heads away from the thick filament backbone towards thin filaments, but the effects of dATP on the myocardium from large mammals has been much less explored. Here we titrated permeabilized porcine myocardium in relaxing solution with a series of dATP concentrations ranging from 0 to 100% of the total nucleotide pool and examined myosin and sarcomere structure using small-angle X-ray diffraction.