MEASUREMENT OF NUCLEOTIDE EXCHANGE KINETICS WITH ISOLATED SYNTHETIC MYOSIN-FILAMENTS USING FLASH-PHOTOLYSIS

The kinetics of nucleotide release have been measured at the level of isolated synthetic myosin filaments. This was achieved by displacing a rhodamine nucleotide analog from a filament by flash photolysis of ca ged-ATP with selective observation using total internal reflectance fl uorescence microscopy. The procedure gave improved time resolution ove r previously used flow methods. Kinetics were measured both in the pre sence of the ADP analog and during steady-state hydrolysis of the ATP analog, These studies open the way for kinetic measurements during act in filament sliding on myosin tracks.