The isotropic-nematic transition and the phase separation of the tobacco mosaic virus particles with polysaccharide

The isotropic-nematic transition of the tobacco mosaic virus (TMV) particle s by polysaccharide is related to a high inhibitory activity against TMV in fection. We study the process of the isotropic-nematic transition of the TM V particles as a function of the polysaccharide concentration by Monte Carl o simulations in three-dimensional continuous space. In these simulations, we simplify the TMV particles and the polysaccharide molecules as the hard spherocylinders and semirigid chains, respectively, and we assume the simpl e interactions for the TMV particles and the polysaccharide chains. In our simulation, with increasing concentration of the polysaccharide the homogen eously dispersed TMV particles begin to segregate without orientational ord ering, that is isotropic phase separation, and then transform to the nemati c state of the TMV particles. The isotropic-nematic transition is caused by simple interactions such as the excluded volume effect, and the complicate d biological interaction is not necessary. (C) 1999 American Institute of P hysics. [S0021-9606(99)50528-X].