Hardware-based anti-Brownian electrokinetic trap (ABEL trap) for single molecules: Control loop simulations and application to ATP binding stoichiometry in multi-subunit enzymes.

The hardware-based Anti-Brownian ELectrokinetic trap (ABEL trap) features a feedback latency as short as 25 µs, suitable for trapping single protein molecules in aqueous solution. The performance of the feedback control loop is analyzed to extract estimates of the position variance for various controller designs. Preliminary data are presented in which the trap is applied to the problem of determining the distribution of numbers of ATP bound for single chaperonin multi-subunit enzymes.