Counter-screen system comparing skeletal muscle myosin activity to cardiac muscle myosin activity in drug studies
Add the S1 fragment to actin filaments to determine actin filament polarity in electron microscopy applications

Skeletal myosin S1 fragment is prepared by digesting skeletal myosin MY02 with -chymotrypsin in the presence of EDTA to liberate the soluble S1 fragment.

• Formulation: supplied as lyophilized powder
• Composition: when reconstituted to 5 mg/ml, the buffer composition is: 20 mM PIPES pH 7.0, 30 mM KCl, 1 mM EDTA, 5% (w/v) sucrose and 1% (w/v) dextran

Skeletal myosin S1 fragment is produced from rabbit skeletal muscle myosin that is ≥90% pure MY02.

The purified myosin S1 fragment remains biologically active in a calcium-stimulated ATPase assay using a soluble sarcomere system (see datasheet). Briefly, the skeletal thin filament complex (STFC) is assembled to mimic muscle thin filaments. Skeletal muscle myosin S1 fragment is added in sub-stoichiometric amounts, and ATP with calcium initiates the reaction. Quality controls ensure that in the absence of calcium, STFC blocks myosin ATPase; the addition of 10 μM calcium relieves inhibition by disrupting the STFC, allowing myosin–actin interaction and ATPase activation.