Can energy landscape roughness of proteins and RNA be measured by using mechanical unfolding experiments?

Abstract

By considering temperature effects on the mechanical unfolding rates of proteins and RNA, whose energy landscape is rugged, the question posed in the title is answered in the affirmative. Adopting a theory by Zwanzig [Zwanzig, R. (1988) Proc. Natl. Acad. Sci. USA 85, 2029-2030], we show that, because of roughness characterized by an energy scale epsilon, the unfolding rate at constant force is retarded. Similarly, in nonequilibrium experiments done at constant loading rates, the most probable unfolding force increases because of energy landscape roughness. The effects are dramatic at low temperatures. Our analysis suggests that, by using temperature as a variable in mechanical unfolding experiments of proteins and RNA, the ruggedness energy scale epsilon, can be directly measured.