Thermal unfolding of myoglobin in the Landau-Ginzburg-Wilson approach

Abstract

The Landau-Ginzburg-Wilson paradigm is applied to model the low-temperature crystallographic C$\alpha$ backbone structure of sperm whale myoglobin. The Glauber protocol is employed to simulate its response to an increase in ambient temperature. The myoglobin is found to unfold from its native state by a succession of $\alpha$-helical intermediates, fully in line with the observed folding and unfolding patterns in denaturation experiments. In particular, a molten globule intermediate is identified with experimentally correct attributes. A detailed, experimentally testable contact map is constructed to characterise the specifics of the unfolding pathway, including the formation of long range interactions. The results reveal how the unfolding process of a protein is driven by the interplay between, and a successive melting of, its modular secondary structure components.