THIS PROJECT PROPOSES TO DETERMINE ATOMIC PARTIAL CHARGES FOR COMMONLY OCCURRING AMINO ACIDS, THE BUILDING BLOCKS OF PROTEINS, FROM EXPERIMENTAL DATA.

THIS PROJECT PROPOSES TO DETERMINE ATOMIC PARTIAL CHARGES FOR COMMONLY OCCURRING AMINO ACIDS, THE BUILDING BLOCKS OF PROTEINS, FROM EXPERIMENTAL DATA. THESE CHARGES ARE NECESSARY PARAMETERS FOR THE FORCE FIELDS USED IN MOLECULAR MODELING STUDIES OF PROTEINS. PREVIOUSLY, SUCH CHARGES HAVEBEEN DERIVED USING QUANTUM MECHANICAL AND OTHER THEORETICAL TECHNIQUES. AS THE ENERGIES, AND THUS CONFORMATIONS, OF PROTEINS ARE BELIEVED TO BE HEAVILY INFLUENCED BY CHARGE- CHARGE INTERACTIONS WITHIN THESE MOLECULES, IT IS VERY IMPORTANT THAT THE CHARGE PARAMETERS USED IN MOLECULAR MECHANICS AND DYNAMICS CALCULATIONS BE AS ACCURATE AS POSSIBLE. WITH RECENTLY DERIVED METHODS, THE NECESSARY CHARGES FROM HIGH ACCURACY X-RAY CRYSTALLOGRAPHIC ARE AVAILABLE. THE CHARGES SO DETERMINED WILL SERVE A NUMBER OFPURPOSES: THEY WILL BE USED IN AN IMPROVED FORCE FIELD FOR FUTURE MOLECULAR MODELING STUDIES OF PROTEINS, AND THEY WILLSERVE AS A CONTROL SET OF DATA WITH WHICH TO COMPARE THE RESULTS OF THEORETICAL CHARGE CALCULATIONS. BY COMPARING CHARGE SETS, THEORETICAL TECHNIQUES (DETERMINATION OF AN OPTIMAL BASIS SET, ACCOUNTING FOR THE EFFECTS OF HYDROGEN BONDING, ETC.) CAN BE IMPROVED, ULTIMATELY MAKING THESE METHODS MORE RELIABLE FOR CHARGE DETERMINATIONS IN THOSE CASES FOR WHICH AN EXPERIMENTAL DETERMINATION IS INFEASIBLE.