Probing structural and dynamical transitions in polymer globules by force

The dynamics of proteins and biopolymers play a crucial role in their function. By using Brownian dynamics we show that polymer globules, which serve as a model system for proteins, undergo a size-dependent dynamical transition from a liquid-like state at high T to a frozen state at low T with a relaxation time that diverges at the transition point. Furthermore, a stretch-induced melting transition is shown to be readily controlled by external forces that exploit the polymer connectivity to modify the size of the globule. This pathway could be a general route to enhance the rate of conformational changes in naturally occurring biopolymers.