Analysis of single-molecule mechanical recordings: application to acto-myosin interactions

Several laboratories have now developed methods to make single-molecule mec hanical recordings from interacting pairs of biological molecules. The mech anical work done (product of force and distance) by a single biomolecular i nteraction is usually of the same order as thermal energy. Recordings made from nonprocessive, intermittently interacting, molecular motors such as ac to-myosin therefore contain a large background of thermal noise. We have ap plied Page's test to analyse mechanical interactions between muscle myosin II's and F-actin recorded using an optical tweezers based single-molecule m echanical transducer. We compare Page's test with other variance-based meth ods and find it to be a robust method for analysing both simulated and real data sets. We discuss some of the problems associated with automatic detec tion of transient mechanical events in noisy data signals, and show that if the start and end points of individual events are known accurately then th e events may be synchronised and combined to give more detailed information about different mechanical states. (C) 2001 Elsevier Science Ltd. All righ ts reserved.