| Different sequence of amino acids, the structure of peptide is changed. Structure determines its property and function of the material. To study the relationship of the structure with properties and function of peptides have important significance. It can help us to better understand the efficacy of various amino acids, so as far as possible to synthesis better physiologically active peptides. Nowadays, heavy metal ions pollution becoming a more and more serious problem. It caused serious damage for human health and ecological environment. So how to detect the heavy metal ions effectively is of great significance in environmental science, biological science and medicine, etc. Current chemical sensor used for determination of heavy metal ions development more and more quickly duo to the chemical sensor has the advantages of high sensitivity, high selectivity and real-time strong, etc. The syudy of fluorescent chemical sensors, colorimetric sensors and electrochemical sensor developed especially striking. The chemical sensor based on peptide is widely used in the field of detection of heavy metal ions. Because it prove to be a good solubility in water, can be easily sythesized via Fmoc-solid phase peptide sythesis(SPPS) and allows conjugation to appropriate systems of biological interest.Based on the principle of the chemical sensors, we have designed and synthesized five chemical sensors which based on peptide motif. Then the interaction of metal ions with them were investigated, respectivily. The main content are as follows:1. The investigation of a high selectivity ratiometric fluorescent chemosensor for Cd2+A ratiometric fluorescent chemosensor Dansyl-Cys-Pro-Pro-Cys-Trp-NH2(Dansyl-P5)was synthesized by SPPS. Dansyl is fluorophore. The interaction between metal ions and D-P5 was studied by fluorescence and CD spectroscopy. The result showed that Dansyl-P5 displayed high selectivity for Cd2+ and exhibited fluorescence increasing upon the adding of Cd2+. The binding ratio of Dansyl-P5 to Cd2+was 2:1 and the detection limit was found to be 11.5 n M, the association constant was 3×1011 mol-2·L2. The sensor is sensing by FRET. The study of the influence of different p H values showed that the most appropriate testing condition was in the neutral.2. The investigation of a high selectivity and sensitivity colorimetric and UV chemosensor for Hg2+ in nano gold solutionBecause of the particular reaction between Hg2+ and-SH, a new peptide(HOOC-Cys-Pro-Pro-Cys-NH2) for metal ions has been designed and synthesized via Fmoc solid-phase peptide synthesis. The interaction between metal ions and P4 was studied by UV-visible and CD spectroscopy via unmodified nano gold solution. The result showed that it has reversible and highly selective and sensitive recognition toward Hg(II) over other commonly coexistent metal ions. The UV-visible and color of nano gold was influenced by the amount of Hg(II). The peptide exhibited a stable response for Hg2+ in the range 0-1 μmol·L-1 with a detection limit of 0.52 nmol·L-1. The study of the influence of different p H values showed that the most appropriate testing condition was in the subacidity solution.3. Synthesis of a pentapeptide Pro-Gly-His-Glu-Tyr and its interaction with copper(II) ionHis and Glu are important binding sites between some protein and Cu2+ in human body. Besides the structure of Pro-Gly can stabilize the β secondary structure of peptide. Tyr is fluorophore. So a new pentapeptide Pro-Gly-His-Glu-Tyr was synthesized via Fmoc solid-phase peptide synthesis. the molecular weight determined by ESI-MS is consistent with its theoretical value. The interaction between metal ions and pentapeptide was studied by fluorescence spectroscopy. The result showed that Cu2+ had a high-efficiency fluorescence quenching, but other commonly metal ions only have a little quenching effects. This specific role towards to Cu2+ is determined by the unique amino acid sequence of the pentapeptide. The fluorescence spectral results indicate that the possible quenching mechanism of the pentapeptide by Cu2+ was a static quenching, and their association constant Ka is 5.54×104. We can design a selective fluorescence chemical sensor for Cu2+ via the property of this pentapeptide.4. The synthesis of Ferrocenyl-peptide and the interaction with Hg2+ by electrochemical methodIn this paper, Fc-Cys-Pro-Pro-Cys(Fc-P4) was synthesized via Fmoc solid-phase peptide synthesiser. The products were characterized by EIS-MS, the results was correspond with the theory molecular mass. Besides, the cyclic votammetry(CV) was carried out to investigate the interaction between Fc-P4 and Hg2+. The results indicated that the Fc-P4 exhibited a higher response to Hg2+ than other metal ions. In the presence of Hg2+, the peak current decrease was observed in the experiment. The influence of scan rate was investigated too. Results show that the peak current was increased with the increased of scan sweep rate, the peak current had good linear relationship with sweep rate. By the influence experiment of scan rate, it indicated that the electrode reaction process was controlled by adsorption.5. The investigation of a high selectivity ratiometric fluorescent chemosensor for Ag+A ratiometric fluorescent chemosensor Dansyl-P5(Dansyl-Glu-Cys-Glu-Glu-Trp)was synthesized by SPPS. The interaction between metal ions and D-P5 was studied by fluorescence. The result showed that Dansyl-P5 displayed high selectivity for Ag+ and exhibited FRET upon the adding of Ag+. The study of the influence of different p H values showed that the most appropriate testing condition was in the neutral, the detection limit was found to be 0.53 μmol·L-1. |
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