Studies on the Synthesis and Degradation of Light and Heavy Chains of Cardiac Myosin

The relative rate of degradation of the light and heavy chains of cardiac myosin was studied by the double isotope technique in which a single injection of [3H]leucine was administered 12 days prior to [14C]leucine in rats. As indicated by 14C:3H ratios of the purified myosin fractions, the light and heavy chains were degraded at heterogeneous rates, the heavy chains having a turnover rate twice that of the light chains.