Analysis of reactant interactions in ribonuclease A active site

Analysis of reactant interactions in ribonuclease A active site 

Currently the most advanced theoretical models of enzyme reactions may be obtained within various variants of supermolecular LCAO MO SCF approach yielding total energy of the system only, without providing much insight into the nature of reactant interactions with the active site residues. 

The precise knowledge of major physical components involved in such interactions is essential to understand biological function of enzyme active site residues and derivation of simplified methods representing environmental effects in chemical reactions. Therefore we attempted to analyze the nature of intermolecular forces between reactants at various stages of enzyme reaction and different forms of catalytic residues. 

As the model system for this study (fig. 3) we selected the first stage of transphosphorylation reaction proceeding in ribonuclease A, using reactant 

Activation energy changes A for the first reaction stage (R2 PTTS3) resulting from protonation of HIS 12, HIS 119 and LYS 41 (in [kcal/mol]). R indicates closest intermolecular 

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