2,3-Butanedione monoxime (BDM) as a myosin inhibitor

2,3-Butanedione monoxime (BDM) is the well-characterized, low-affinity, non-competitive inhibitor of skeletal muscle myosin-II. It has been widely used at millimolar concentrations in cell biological experiments with the assumption that it is an ATPase inhibitor of the myosin superfamily. To determine the usefulness of BDM as a general myosin inhibitor, the ATPase activities of the motor domains of skeletal muscle myosin-II, Acanthamoeba myosin-IC, human myole, chicken myosin-V, and porcine myosin-VI were measured in the presence of 0-40 mM BDM. BDM inhibits skeletal muscle myosin-II, but it does not inhibit the ATPase activity of the other myosins. Therefore, BDM is not a general inhibitor of the myosin ATPase. BDM has a broad effect on many non-myosin proteins (many uncharacterized), and thus should not be used in whole-cell experiments as a myosin inhibitor.