Investigation On Interaction Of Prulifloxacin With Protein

Investigating the binding mechanism of toxic materials and drugs with protein has many importances in toxicology and pharmacokinetics. Thus, it has been an interesting research field of life sciences, chemistry and clinical medicine. The efficiency of treatment of disease is directly affected by the combining location and functionary mechanism of drugs in body. Therefore, it is necessary to investigate the combining location and functionary mechanism between pharmaceutical molecules and biomacromolecule. It also can make sure the security, reasonability and availability when drugs are used by patients. In this dissertation, on the basis of the previous research, the fluorescence spectroscopy combined with UV/Vis absorption spectroscopy were used to investigate the interaction of prulifloxacin with protein.This dissertation consists of five chapters:Chapter 1: The structures, functions and natures of proteins briefly introduced. The contents and methods of interaction of different kind of small ligands with protein reviewed.Chapter 2: Prulifloxacin(PUFX) is a kind of new oral taking antibiotic of fluoroquinolone. Congugation reaction of prulifloxacin with trypsin in Britton–Robinson buffer solution of pH 7.96 was analysized by UV/Vis spectrophotometry and fluorescence spectrometry. The intrinsic fluorescence of trypsin was strongly quenched by prulifloxacin. This effect was rationalized in terms of a static quenching procedure. The binding parameters have been evaluated by fluorescence quenching methods. Negative values⊿G0 for the formation of prulifloxacin–trypsin complex implied that both hydrogen bonds and hydrophobic interactions might play a significant role in prulifloxacin binding to trypsin. The binding distances deduced from the efficiency of energy transfer was 0.84 nm for prulifloxacin– trypsin. Furthermore, association constants and binding mechanism were successfully derived from the fluorescence spectra. UV/Vis detections supported a change in the secondary structure of proteins caused by the interaction of prulifloxacin with trypsin.Chapter 3: The interaction between prulifloxacin (PUFX), a kind of new oral taking antibiotic and pepsin, a kind of enzyme in the stomach has been investigated in vitro under a simulated physiological condition by different spectroscopic methods. The intrinsic fluorescence of pepsin was strongly quenched by prulifloxacin. This effect was rationalized in terms of a static quenching procedure. The binding parameters have been evaluated by fluorescence quenching methods. The negative value of⊿G0 reveals that the binding process is a spontaneous process. The binding distance R between donor (pepsin) and acceptor (prulifloxacin) was obtained according to the F?rster's resonance energy transfer theory and found to be 0.95 nm. The results obtained herein will be of biological significance in pharmacology and clinical medicine.Chapter 4: The interaction between prulifloxacin (PUFX) and human serum albumin (HSA) was investigated under simulated physiologic conditions with fluorescence spectra. The fluorescence quenching process of HSA may be mainly governed by a static quenching mechanism. The apparent binding constant Kb between PUFX and HSA at different temperatures were 2.08±1.04, 2.74±0.50, and 4.98±1.61×10⁸ L mol^-1. The thermodynamic parameters, with a negative value of⊿G0, revealed that the binding is a spontaneous process. A binding distance R of 1.19 nm between donor and acceptor was obtained from the FÇ’rster energy transfer theory.Chapter 5: Conclusion and outlook.