Several different point mutations in the myosin heavy chain and light chains (LC) cause the human heart disease known as familial hypertrophic cardiomyopathy (FHC). The goal of these researchers was to understand the biophysical and biochemical basis of the mutant phenotypes by performing site-directed spin labeling (SDSL) and electron paramagnetic resonance (EPR) spectroscopy on FHC-mutant RLC in muscle fibers. The expectation was to determine the effect of the FHC mutations on the protein structure by simulating the mutations in crystal structures of myosin to ascertain whether or not the tertiary structure of the protein is affected by the mutation. Using the molecular modeling program Insight II to construct energy-minimized models for the LC domain containing these rat VRLC mutations, Professor Roopnarine looked forward to engineering cysteine residues on the crystal structures of the protein to determine if it is an appropriate site for minimal protein structural perturbation.

This would allow the researchers to develop an experimental design of spectroscopic studies. The simulated Cys mutants were then to be used as the background for the FHC mutations. Following this work, the molecular dynamics program was expected to simulate the dynamics of a spin label attached to the Cys, in order to determine if the site for labeling would detect specific motional changes within the protein.

  Preliminary work with the FHC-RLC mutations would allow Professor Roopnarine to visualize probable structures and to perform molecular dynamics simulations to be compared directly with EPR spectroscopic data. The results of this were expected to suggest that the FHC mutation perturbs the flexibility of the region that connects the two principal lobes of the RLC.