The purpose of this proposal is to carry out computer simulations and related theoretical calculations of electron spin (paramagnetic) resonance (ESR or EPR) and nuclear magnetic resonance (NMR) phenomena in a number of systems of biological interest. Recently experimental techniques in these areas have made strides. To get the maximum amount of information from the experimental data while using realistic theoretical models, it is necessary to perform involved computations on large computers. These simulations tax the computer core memory and the computer time required for analyses to their ultimate limit. It is proposed to develop computational methods like the conjugate gradient method and the finite element method to overcome such difficulties in simulating magnetic resonance spectra. Using these methods it is planned to study CW and two- dimensional ESR spectra of model membranes, ESR spectra of transition metal complexes of biological systems and NMR of paramagnetic metal-nucleotide complexes bound to ATP-utilizing enzymes. Comparison of simulated spectra with experimental data will determine magnetic and motional parameters and parameters governing strengths of the membranic environment of spin labels (in ESR). NMR calculations of paramagnetic metal- nucleotide complexes will help in removing ambiguities in the metal-nucleotide distance determinations. This in turn would help in understanding the catalytic activities of the enzymes on a molecular basis. Our analysis will thus give information on the dynamical molecular structure of these systems. Theoretical calculations and computer simulations such as those proposed here should go a long way towards clarifying our understanding of biological systems at a deeper molecular level and thus leading to a better understanding of structure-function relationships.
