BTS is an inhibitor of skeletal muscle myosin II ATPase activity that reduces the affinity of ADP-myosin for actin.
1 It inhibits calcium-stimulated ATPase activity of rabbit muscle myosin subfragment 1 (S1) in an actin-independent manner with an IC
50 value of approximately 5 μM. It is selective for calcium-stimulated myosin II over human platelet myosin II, kinesin, pyruvate kinase, and lactate dehydrogenase at 100 μM. BTS (2 μM) inhibits the activity of skeletal muscle myosin, reversibly reducing the sliding velocity of heavy meromyosin in a gliding-filament assay. It inhibits isometric calcium-activated tension in isolated fast-twitch rabbit psoas muscle fibers (IC
50 = ~3 μM) but not in isolated slow-twitch rat trabeculae and papillary cardiac muscle. BTS is also an intermediate in the synthesis of sulfonamides.
2