Spectrofluorometric study on the interaction of papaverine with polyribonucleotides

Studies on the interaction of papaverine [opiate alkaloid] with some polyribonucleotides [poly A, poly C, and poly U] at the molecular level was done using fluorescence quenching method to through some light on the mechanism of action of this drug. Binding parameters like; the number of binding sites on one polymer molecule [n], the equilibrium constant [k], and the well known delta S°, delta H°, and delta S°, together with theoretical treatment of the observed thermodynamic parameters relative to the base. stacking and destacking of the polymers and their complexation with papaverine. It was concluded that a charge transfer [CT] interaction occurs between the lone pair electrons of papaverine nitrogen and some electrophilic site at the nucleic acid bases, accompanied by specific conformational perturbations and deformations on the poly nucleotides sequences from papaverine binding effect

Cholinergics - aromatic amino acids and amines interactions a spectroscopic investigation

UV absorption spectroscopic methods were used for the studies of interaction between some cholinergic compounds; acetylcholine, acetyl- beta methylcholine, and carbacholine, with indolic compounds; L-tryptophan and tryptamine in order to elucidate the mechanism of action for these neurohumoral compounds at the molecular level. This was done through calculation of thermodynamic parameters [K, delta G°, delta H°, and delta S°] for 1:1 complex which is predominated. The K values were mostly less than one and were found to be temperature and wavelength dependent, which reflect the values of other thermodynamic parameters. A charge transfer [CT] complex formation between cholinergic compounds [electron- donors], and L- tryptophan and tryptamine [electron- acceptors] was concluded