Electric field modulation of the motility of actin filaments on myosin-functionalised surfaces

We investigated the difference in electrically guided acto-myosin motility on two surfaces. Rabbit skeletal muscle heavy meromyosin (HMM) was absorbed onto surfaces coated with Nitrocellulose (NC) and Poly(butyl methacrylate) (PBMA). A modified in vitro motility assay with sealed chambers for the insertion of electrodes allowed an electrical field to be applied across the flow cell. On all surfaces a small increase in velocity and general guidance of the actin filaments towards the positive electrode is seen at field strengths in the range of similar to 3000 - 4000Vm(-1). A large increase in velocity was observed at similar to 5000Vm(-1) and a significant change in the velocity of the actin filaments present in field strengths higher than this. NC supported the highest percentage of motile filaments and at a field of 8000Vm(-1) reached similar to 66%. PBMA however supported the least percentage of motile filaments and irregular motility was observed even at higher fields where guidance was expected to be strong. The change in velocity in the range of fields tested varied significantly on the surfaces with NC displaying a 46% increase from 0 to 8000Vm(-1) whereas on PBMA this value was just 37%.