Kinetic properties and the electric field effect of life helix–coil transition of poly(γ‐benzyl <scp>L</scp>‐glutamate) determined from dielectric relaxation measurements

Abstract

Abstract Dielectric relaxation of poly(γ‐benzyl L ‐glutamate) in solution has been studied in the 5 kcps‐10 Mcps range for various values of the helix content. The results give first experimental evidence for three effects of major significance. ( 1 ) The system exhibits dielectric relaxation due to a chemical rate process (namely helix formation). This confirms recent theoretical predictions. ( 2 ) The mean relaxation time τ* of the helix–coil transition could be evaluated as a function of the degree of transition. The results are in excellent agreement with a previously developed theory. At the midpoint of transition it is found τ* max = 5 × 10 −7 sec. The elementary process of helical growth turns out to be practically diffusion‐controlled (with a rate constant of hydrogen bond formation of 1.3 × 10 10 sec −1 ). ( 3 ) There is a considerable electric field effect of the helix–coil transition. This indicates that conformation changes in biological systems could be potentially caused by direct action of an electric field.