Optical tweezers have been used extensively to measure the mechanical properties of individual biological molecules. Over the past 10-15 years optical trapping studies have revealed important information about the way in which motor proteins convert chemical energy to mechanical work. This paper focuses on studies of the acto-myosin motor system that is responsible for muscle contraction and a host of other cellular motilities. Myosin works by binding to filamentous actin, pulling and then releasing. Each cycle of interaction produces a few nanometres movement and a few piconewtons force. Individual interactions can be observed directly by holding an individual actin filament between two optically trapped microspheres and positioning it in the immediate vicinity of a single myosin motor. When the chemical fuel (adenosine triphosphate or ATP) is present the myosin undergoes repeated cycles of interaction with the actin filament producing square-wave like displacements and forces. Analysis of optical trapping data sets enables the size and timing of the molecular motions to be deduced.

Date Published: 13 September 2007
PDF: 11 pages
Proc. SPIE 6644, Optical Trapping and Optical Micromanipulation IV, 66440B (13 September 2007); doi: 10.1117/12.736722

Published in SPIE Proceedings Vol. 6644:
Optical Trapping and Optical Micromanipulation IV
Kishan Dholakia; Gabriel C. Spalding, Editor(s)