Solution conformation of gibberellic acid as determined by NMR and molecular mechanics calculations

The proton and carbon assignments of the plant hormone gibberellic acid (GA3) in DMSO-d6 were determined. Dynamical and conformational properties of GA3 in solution were studied on the basis of proton and carbon dipolar relaxation contributions. A new experimental method for the simultaneous detection on surrounding nuclei of labile protons of direct and cross-relaxation contributions was proposed and applied to study the conformation of GA3. Finally, the GA3 structures obtained from experimental NMR parameters, energy minimization theory, and X-ray crystal diffraction are compared.