Spectroscopic Studies On The Interaction Of Some Antibiotics With Protein And Effect Of The Coexisting Substances On The Reaction

The interactions between small drug molecules and protein have caused all the attentionof scientific research personnel in recent years. Especially in the field of the chemical andbiological, it has become a very active subject. Serum Albumin and Hemoglobin wereconsidered as carrier in this paper, this paper has carried on the study of the bindingmechanism between a new generation of antibiotics and protein. In addition, the effect ofsome antibiotics as well as metal ion on the interaction has been studied. The research contenthas been divided into five chapters:Chapter one: The process of efficacy of drugs in blood plasma and the importance ofprotein were reviewed. Accordingly, the research methods as well as its research progress tostudy the interaction between drug molecules and serum albumin were reviewed, with43literatures quoted.Chapter two: Binding reaction between cefpirome sulfate （CPS） and bovine serumalbumin （BSA） was investigated by fluorescence spectroscopy, synchronous fluorescencespectroscopy and resonance light scattering （RLS） at different temperatures. Results showedthat both fluorescence and RLS of BSA reduced with the concentration of CPS increased, andthe effect between CPS and BSA was static fluorescence quenching process with F resterspectroscopy energy transfer. The scope of apparent binding constants （K_a） was10⁴; thecorresponding binding site value （n） in the binary systems was1; the binding distances （r）were much smaller than7nm and the primary binding site for CPS was located at siteⅠinsub-domain ⅡA of BSA. Besides, the electrostatic attraction played an important role on theconjugation reaction of BSA and CPS. The values of Hill’s coefficients were less than1,which indicated that there was some negative cooperative effect. Studies utilizingsynchronous spectra showed that the conjugation reaction between PS and BSA would affectthe conformation of BSA, leading to the polarity around BSA strengthened and thehydrophobicity weakened.Chapter three: Colistin sulfate （CS） can quench the fluorescence of bovine serum albumin（BSA） in aqueous solution at pH7.40. The static fluorescence-quenching process betweenBSA and CS was confirmed and the binding constant, the number of binding sites, andthermodynamic data for the interaction between BSA and CS were also obtained. Resultsshowed that the order of magnitude of binding constant （K_a） was10⁴, and the number of binding site （n） in the binary system was approximately equal to1, electrostatic force playedan important role on the conjugation reaction between BSA and CS. On the basis of theF rster theory of the resonance energy transfer, the binding distance （r） between CS and BSAwas less than7nm. Comparing the quenching of protein fluorescence excited at280nm andat295nm and from the site marker replacement experiments, it was shown that the primaryCS binding site was located in the sub-domain IIA （site I） of BSA. In addition, the effects ofcommon metal ions on the binding constants of CS-BSA complex were also discussed. It wasshown that, excepting Cu²⁺, high metal ion concentrations improved the CS efficacy.Chapter four: The interaction between moxifloxacin （MXFX） and bovine serum albumin（BSA） was investigated at different temperatures by fluorescence spectroscopy. Resultsshowed that MXFX could quench the intrinsic fluorescence of BSA strongly, and thequenching mechanism was a static quenching process with F rester spectroscopy energytransfer. The electrostatic force played an important role on the conjugation reaction betweenBSA and MXFX. The order of magnitude of binding constants （Ka） was10⁴, and the numberof binding site （n） in the binary system was approximately equal to1. The binding distance （r）was less than3nm and the primary binding site for MXFX was located in sub-domain IIA ofBSA. Synchronous fluorescence spectra clearly revealed that the microenvironment of aminoacid residues and the conformation of BSA were changed during the binding reaction. Inaddition, the effect of some antibiotics on the binding constant of MXFX with BSA was alsostudied.Chapter five: The interaction between moxifloxacin （MXFX） and Bovine Hemoglobin（BHb） was investigated at different temperatures by fluorescence spectroscopy. Resultsshowed that the quenching mechanism of MXFX on BHb was a static quenching process withF rester spectroscopy energy transfer. The primary binding for MXFX was located at β-37Tryptophan residue in hydrophobic cavity of BHb; besides, weak negative cooperativity wasfound in drug’s binding with BHb. Most antibiotics had no effect on the system ofBHb-MXFX except quinolone antibiotics, and the syetem had a good stability.