Single-Molecule Studies of Trapped Biomolecules in Solution with the ABEL Trap

Abstract

Studies of single fluorescent molecules, proteins, or enzymes has provided a wealth of physical and chemical information on the nanoscale devoid of ensemble averaging. To study a single biomolecule in solution without surface attachment or confinement, the Anti-Brownian ELectrokinetic (ABEL) trap provides real-time suppression of Brownian motion, and provides time-averaged uniform pumping intensity for long-time observation without the use of laser tweezers (Cohen and Moerner, Opt. Express (2008)). In recent applications, we have explored the photodynamics of the antenna protein allophyocyanin (Goldsmith et al., Nature Chem. (2010)) and extracted ATP number distributions for single multi-subunit chaperonin enzymes (Jiang et al., PNAS (2011)). This device has also been used to follow electron transfer dynamics for individual nitrite reductase enzymes (Goldsmith et al., PNAS (2011)), providing a new window into light-driven photodynamics, cooperativity, and enzymatic mechanisms.