We study the effect of an intrinsic curvature on the mechanical property of two-dimensional semiﬂexible biopolymers and ﬁnd that it can induce a discontinuous transition in extension. At zero temperature, we accurately show that the extension of an intrinsically curved semiﬂexible biopolymer of ﬁnite length can undergo a multiple-step discontinuous transition regardless of bending rigidity. The transition is accompanied by unwinding loops, and the critical force reaches a limit quickly with decreasing number of loops so that, in the experiment, it is possible to observe the almost simultaneous opening of several loops. However, the ﬂuctuation or conﬁgurational average at a ﬁnite temperature suppresses the sharp transition so that there is no discontinuous transition in a system of ﬁnite size. However, our results obtained from Monte Carlo simulation reveal that, at a ﬁnite temperature, the extension of a biopolymer can undergo a one-step ﬁrst-order transition in the thermodynamical limit if the biopolymer has a sufﬁciently large bending rigidity. The critical force increases with increasing intrinsic curvature or bending rigidity.
Journal of the Physical Society of Japan 83, 044802(8pages)