Energy flow in proteins

Energy flows anisotropically through the residues and vibrational states of globular proteins. A variety of experimental and computational studies have identified energy transport channels traversing many residues, in some cases connecting functional regions, potentially important in allostery, and in other cases having no apparent function. This property and the diffusion of energy in proteins are mimicked by transport on a percolation cluster. I review work that addresses connections between globular proteins, percolation clusters, and the similarity of energy flow and thermal transport in these systems. I also review experimental and theoretical studies of the anisotropic flow of energy through the vibrational states of a protein, a property that also can be understood by comparison with simple model disordered systems.