Molecular dynamics calculations of the electrostatic properties of tubulin and their consequences for microtubules

We present the results of molecular dynamics computations based on the atomic resolution structures of tubulin published as 1TUB and 1 JFF in the Protein Data Bank. Values of net charge, spatial charge distribution and Cartesian dipole moment components are obtained for the tubulin alpha-beta heterodimer. Physical consequences of these results and subsequent computations are discussed for microtubules in terms of the effects on test charges, test dipoles, and neighboring microtubules. Our calculations indicate typical distances over which electrostatic effects can be felt by biomolecules, ions, and other microtubules. We also demonstrate the importance of electrostatics in the formation of the microtubule lattice and the tubulin-kinesin binding strength.