| Deoxyribonucleic acid (DNA) and protein are important genetic substance of life,which play a key role in biological processes. By the development of genomics, moreand more functional genes and functional proteins were discovered. However, theyare the goal of exogenous ligands, especially, is targeting molecule of drugs, they canbe used to research for their pharmacological activity and toxicity. Hence, theinvestigation of interaction between ligands and biomacromolecules still is a hot topicin biochemistry and life sicence fields. Meanwhile, with the rapid development ofvarious excellent properties of nano-materials, the applications have drawnwidespread concerns in the field of biochemistry. While, the conformations ofbiomacromolecules maybe have been influenced when they interact withnano-materials, for biomacromolecules, its conformation determines the expression ofbiological function. Therefore, to understand and research the interaction betweensmall ligand molecules and DNA or protein comprehensively, it is an important basisfor evaluating the expression of genetic information, biological function andphysiological activity. Based on this, the mainly work are as following:1. The interaction between2-phenylpyrazolo [1,5-c] quinazoline (PQ) andDNA, EcoRI under the physiological condition was investigated by usingmulti-spectroscopic techniques, atom force microscopy and gel electrophoresis. Thethermodynamic parameters were estimated and discussed in detail. The results offluorescence quenching experiments indicated that the main interactive force betweenPQ and DNA was hydrophobic interaction and it was a static quenching process.Potassium iodide and ssDNA quenching studies together with circular dichroismspectra implied the groove binding of PQ with DNA. AFM and gel electrophoresisexperiments suggest that there are no major conformational changes in DNA uponinteraction with PQ. In addition, UV-vis absorption titration of DNA bases confirmedthat PQ bound with DNA mainly through minor groove interaction and preferentiallyinteracted with adenine and thymine. Similarly, hydrophobic interaction is thepredominant intermolecular forces stabilizing the PQ-EcoRI complexes. Thesecondary structures of EcoRI were changed obviously in the presence of PQ, the results exhibited a reduction of α-helix, but, the enzyme activity of EcoRI was notlost.2. The bindings of9-chloro-2-phenylpyrazolo[1,5-c]quinazoline(PQ-1),2-(4-methoxyphenyl)pyrazolo[1,5-c]quinazoline(PQ-2), and9-chloro-2-(4-methoxyp-henylpyrazolo[1,5-c]quinazoline(PQ-3) into DNA were carried out using UV-visabsorbance spectroscopy, fluorescence spectroscopy and circular dichroism(CD).Contrast to the first work, different substituents of quinazolines which influence theinteraction of quinazoline derivatives with DNA, namely, PQ-1, PQ-2and PQ-3,where the binding modes are established to be intercalative.3. A simple solvent method for synthesis cit-AgNPs and PVP-AgNPs,fluorescence titrimetric method was used to investigate the interaction of AgNPs withbacteriorhodopsin (bR), combining with Hill theory to investigate the cooperativity.The result implied that the process of cit-AgNPs-bR is positive cooperativity, while,PVP-AgNPs-bR is negative cooperativity. FTIR analysis the conformational structureof bR indicated that the content of α-helix of cit-AgNPs-bR increased, whereas, thecontent of helical structures decreases in PVP-AgNPs-bR, it implyed that bR wouldadopt a more incompact conformation state on the surfaces of PVP-AgNPs. |
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