Theoretical Vibrational Spectra of Reaction Intermediates in the Active Site of Guanosine Triphosphate Binding Proteins

Calculations of the structures and energies of intermediates of the enzymatic hydrolysis of guanosine triphosphate, performed by means of quantum mechanics and molecular mechanics (QM/MM), suggest a mechanism for chemical transformations of reaction particles in an active site that assumes an amide-imide tautomerism of the side chain of glutamine residue. Positions of vibrational bands and a corresponding band shift upon isotopic substitution 14 N → 15 N in the side chain of glutamine residue in the active site are predicted for experimental verification of the given mechanism via IR spectroscopy.