  We propose a criterion for optimal parameter selection in coarse-grained
models of proteins, and develop a refined elastic network model (ENM) of bovine
trypsinogen. The unimodal density-of-states distribution of the trypsinogen ENM
disagrees with the bimodal distribution obtained from an all-atom model;
however, the bimodal distribution is recovered by strengthening interactions
between atoms that are backbone neighbors. We use the backbone-enhanced model
to analyze allosteric mechanisms of trypsinogen, and find relatively strong
communication between the regulatory and active sites.
