NONMONOTONIC TEMPERATURE-DEPENDENCE OF THE FLEXIBILITY OF BACTERIOPHAGE FD

We present two experiments that probe the temperature dependence of th e flexibility of the filamentous virus fd by examining aspects of the liquid crystalline nature of fd suspensions. The first measurement is of the temperature variation of the coexisting fd concentrations at th e isotropic-cholesteric phase transition. The second measurement is of the magnetic field induced birefringence or Cotton-Mouton constant in the isotropic phase as a function of temperature. We compare these me asurements with the theoretical treatment of Onsager, Khokhlov-Semenov , and Chen and conclude that the flexibility of fd varies nonmonotonic ally with temperature and has a minimum in persistence length at 35 de grees C. (C) 1996 John Wiley & Sons, Inc.