Mechano-chemical energy transduction in biological systems. The effect of mechanical stimulation on the polymerization of actin: a kinetic study

Mechanical stimulation (forced circulation in narrow tubing) accelerated the rate of polymerization of [rabbit] actin by as much as 10-fold. The increase in the rate was proportional to the intensity of the stimulation for flow rates between 0-3 cm/s. A statistical factor (the orientation of the flowing particles) is apparently influenced by the flow. Comparison of the kinetics of the polymerization of resting and of mechanically stimulated actin solutions showed that both the nucleation and elongation steps were accelerated. Flow oriented not only the oligomeric structures but also the actin monomers. The elongation reaction, also in the flow-stimulated samples, occurred always by the addition of ATP-G-actin (or ATP-containing oligomers) and not by the fusion of ADP-containing oligomeric structures.