Interaction of anthracycline antibiotics with actin and heavy meromyosin.

For the purpose of elucidating the biochemical mechanism of anthracycline cardiomyopathy, the interaction with actin and heavy meromyosin (HMM) was studied. HMM and acto-HMM Mg²⁺-ATPase reactions were inhibited by daunorubicin and adriamycin; but not significantly by aclacinomycin A. The three antibiotics induced G-actin polymerization. Difference absorption spectra showed a direct interaction of adriamycin or aclacinomycin A with actin or HMM. Equilibrium dialysis and spectrofluorometric studies indicated that actin monomer possesses one binding site for adriamycin or aclacinomycin A with the same order of association constants (1.4 – 7.2 × 10⁴ M^?1). Adriamycin exhibited significantly higher affinity for HMM than aclacinomycin A.