| Abstract |
Microtubules (MTs) are proteic polymers showing a hollow cylindrical structure. MTs are composed of alpha-beta-tubulin heterodimers arranged in linear protofilaments. The protofilaments are disposed side by side to form the tubular structure. MTs are part of the cytoskeleton and ubiquitous in eukaryotic organisms, where they perform several vital roles. Theoretical studies have concluded that the tubulin heterodimers have a permanent electric dipole. MTs should then have a significant electric dipolar moment along their axes, and an electrical field of sufficient magnitude should be capable of aligning MTs parallel to the field direction. In our work this was verified experimentally by AFM measurements. Tubulin heterodimers were purified from mouse brains. MTs were obtained by polymerization in vitro and stabilized with taxol. Then they were adsorbed to Poly-L-lysine-coated glass slides, and imaged by AFM. Samples of microtubules adsorbed under and without electric fields of different magnitudes are compared. Although no difference is observed for adsorption under electric fields in the kV/m range, the alignment is clearly observable for fields close to the MV/m range, confirming the existence of a dipolar moment as predicted. Work is undergoing in order to establish the influence of other experimental conditions. (C) 2006 Elsevier B.V. All rights reserved. |
