Studies on the interaction of palmatine hydrochloride with bovine hemoglobin.

The interaction between bovine hemoglobin (BHb) and palmatine hydrochloride (PMT) was investigated at different temperatures using multispectroscopy, as well as the effect of common metal ions (Ca(2+) , Mg(2+) , Zn(2+) , Cu(2+) , Fe(2+) , Fe(3+) , Co(2+) , Ni(2+) ) on the BHb-PMT system. Results showed that the quenching mechanism of PMT on BHb was a static process. The electrostatic force played an important role in the conjugation reaction between BHb and PMT. The order of magnitude of the binding constants (Ka ) was 10(4) , and the number of binding sites (n) in the binary system was ~ 1. The binding distance (r) was ~ 2.44 nm and the primary binding for PMT was located at ß-37 tryptophan in the hydrophobic cavity of BHb. In addition, the Hill's coefficients were ~ 1. Synchronous and circular dichroism spectra revealed that the microenvironment and the conformation of BHb were changed during the binding reaction.

[Modification on the interaction of glipizide with bovine serum albumin by molecular spectroscopy].

In the Tris-HCl buffer solution with pH was 7.40, the interaction between glipizide (Gli) and bovine serum albumin (BSA) was investigated by classical fluorescence spectroscopy with the change of protein as investigation object and elastic scattering fluorescence spectrometry with the change of drugs as investigation object at 293 K and 303 K, the conclusions of the two methods were consistent. Results showed that Gli could quench the intrinsic fluorescence of BSA, and the quenching mechanism was a dynamic quenching process. The hydrophobic force played an important role in the conjugation reaction between BSA and Gli, the binding site mainly located in BSA hydrophobic region and the number of binding site (n) in the binary system was approximately to 1. The values of Hill's coefficients were less than 1, which indicated the weak negative cooperativity in BSA-Gli system. The binding constant (Ka) obtained by elastic scattering fluorescence spectrometric was much larger than the one obtained by classical fluorescence spectroscopy, indiciating that it was more accurate and reasonable when using the change of drug's fluorescence as the research object. At last, the scientificalness of the new method based on elastic scattering fluorescence spectrometric was verified by ultraviolet spectroscopy. The research results showed that there existed insufficiency in analysis of the interaction of drug with protein by classical fluorescence spectroscopy with the change of protein as investigation object, and the fluorescence spectrogram only reflected partial information of the interaction between drug and protein, while the interaction between drug and protein could be better expressed by elastic scattering fluorescence spectrometry with the change of drugs as investigation object.