Hydrolysis of DNA is an important enzymatic reaction , but it is exceedingly difficult to mimic in the laboratory because of the stability of hydrolysis of DNA. In this paper, the cleavage activity of complexes forme... Hydrolysis of DNA is an important enzymatic reaction , but it is exceedingly difficult to mimic in the laboratory because of the stability of hydrolysis of DNA. In this paper, the cleavage activity of complexes formed between Cu(Ⅱ) and four different amino acid or amino acid methyl ester on DNA is studied by gel elec-trophoresis. It is found that DNA could be cleaved by Cu(Ⅱ)-L-His and Cu(Ⅱ)-L-His methyl ester complexes and the efficiency of cleavage is largely dependent on the metal ion-to-ligand ratio. Further experiments show that the cleavage of DNA mediated by Cu(Ⅱ)-L-His complexes occurs via a hydrolytic mechanism and the active chemical species that affects DNA cleavage is proposed to be MI2H+ and ML2H22+.展开更多
The cleavage activity of complexes between copper (Ⅱ) and four different amino acidor amino acid methyl ester on DNA was tested at physioloical pH and temperature., It was found that Cu (Ⅱ)-L-His and Cu (Ⅱ)-L-His m...The cleavage activity of complexes between copper (Ⅱ) and four different amino acidor amino acid methyl ester on DNA was tested at physioloical pH and temperature., It was found that Cu (Ⅱ)-L-His and Cu (Ⅱ)-L-His methyl ester complexes could cleane DNA. The extent ofDNA cleavage is largely dependent on the metal ion-to-ligand ratio. The cleavage of doublestranded DNA mediated by Cu (Ⅱ)-L-His complexes occurs via a hydrolytie mechanism.展开更多
The reaction of bis-[2-amino-4-pheny1-5-thiazolyl] disulfide with 5-nitro-salicylaldehyde in absolute ethanol resulted in the formation of a new Schiff base ligand H<sub>2</sub>L (1). Characterization of t...The reaction of bis-[2-amino-4-pheny1-5-thiazolyl] disulfide with 5-nitro-salicylaldehyde in absolute ethanol resulted in the formation of a new Schiff base ligand H<sub>2</sub>L (1). Characterization of the ligand was performed by FT-IR, <sup>1</sup>H NMR, <sup>13</sup>C NMR, UV-Vis, elemental analysis and single crystal X-ray diffraction. The ligand, (1), possesses a disulfide –S–S– bridge of 2.1121 (3) ? length, and the molecule adopts a cis-conformation around this bond. In the crystal structure of (1), an intramolecular O–H···N hydrogen bond with D… A distance of 2.69 (3) ? was present. The reaction of (1) with Co(NO<sub>3</sub>)<sub>2</sub>·6H<sub>2</sub>O and CuCl<sub>2</sub>·2H<sub>2</sub>O in methanol afforded the corresponding metal complexes. The obtained solids were further investigated by elemental analysis and UV-Vis titration that confirmed the formation of [CoL] and [ClCuHL] complexes. However, recrystallizaion of the Co(II) complex in dimethylsulfoxide caused the complete hydrolysis of the imine bond and afforded a Co(II) complex in which two 5-nitro-salicylaldehyde and two DMSO molecules were coordinated to the central metal in an octahedral fashion. This structure (2) was also confirmed by single crystal X-ray analysis.展开更多
The electrospray ionization mass spectrometry and tandem mass spectrometry investigation showed that the binding sites of Zn^2＋ with oxidized insulin B chain are His 5, His 10, and Arg 22, which lead to the selective...The electrospray ionization mass spectrometry and tandem mass spectrometry investigation showed that the binding sites of Zn^2＋ with oxidized insulin B chain are His 5, His 10, and Arg 22, which lead to the selective cleavages of the peptide bonds at Ash 3- Gin 4, His 5-Leu 6, Gly 8-Ser 9, and Glu 21-Arg 22 of oxidized insulin B chain.展开更多
The interaction of oxidized insulin B chain (B) with cis-[Pd(en)Cl2] (en=ethylenediamine), cis-[Pd-(dtco-3-OH)Cl2] (dtco-3-OH= dithiacyclooctan-3-ol) and CuCl2 was studied by electrospray mass spectrometry. It is disc...The interaction of oxidized insulin B chain (B) with cis-[Pd(en)Cl2] (en=ethylenediamine), cis-[Pd-(dtco-3-OH)Cl2] (dtco-3-OH= dithiacyclooctan-3-ol) and CuCl2 was studied by electrospray mass spectrometry. It is discovered that the binding of Pd(II) complexes and the sites of cleavage are highly dependent on the secondary structure and local environment of B. The hydrolytic cleavage of denatured B by Pd(II) complexes was monitored by HPLC. The reaction is regioselective and follows first order kinetics with half-life of 4.8 days at 40oC. Two amide bonds, i. e. at Leu6-Cys7 and at Gly8-Ser9, which are dose to the two potential Pd(II) binding sites His5 and His10, are selectively cleaved. In the case of Cu(II) ion as promoter, only one cleavage site was observed which is located at Gly8-Ser9 bond. These results provide improved understanding on the design of artificial metallopeptidase.展开更多
A new binuclear complex [Cu2L(OH)](ClO4)3·2H2O has been synthesized and characterized, where L=2,6-bis{[bis-(2-aminoethyl)amino]methyl}-benzene. In the presence of 0.5 mmol/L complex at pH 8.10 and 37°C, t...A new binuclear complex [Cu2L(OH)](ClO4)3·2H2O has been synthesized and characterized, where L=2,6-bis{[bis-(2-aminoethyl)amino]methyl}-benzene. In the presence of 0.5 mmol/L complex at pH 8.10 and 37°C, the complex can efficiently cleavage pBR322 DNA with a rate constant kobs of 1.35×10-4 s-1. The cleavage occurred by a non-oxidative mechanism showing activity to be dependent on pH.展开更多
The electrospray ionization mass spectrometry investigation showed that the binding sites of [ZnL]^2＋, where L is 2-[bis（2- aminoethyl）amino]ethanol, with oxidized insulin B chain are Phel, His5 and Arg22, which le...The electrospray ionization mass spectrometry investigation showed that the binding sites of [ZnL]^2＋, where L is 2-[bis（2- aminoethyl）amino]ethanol, with oxidized insulin B chain are Phel, His5 and Arg22, which lead to the selective cleavages of the peptide bonds at Phe1-Val2, His5-Leu6, Glu21-Arg22, and Arg22-Gly23 of oxidized insulin B chain.展开更多
The complex of Zn[（phen）（dione）Cl]ClO4·H2O （where phen is 1,10-phenanthroline and dione is 1,10-phenanthroline-5,6-dione） has been synthesized and characterized. The interaction of the complex with DNA was ...The complex of Zn[（phen）（dione）Cl]ClO4·H2O （where phen is 1,10-phenanthroline and dione is 1,10-phenanthroline-5,6-dione） has been synthesized and characterized. The interaction of the complex with DNA was investigated using UV absorption, fluorescence spectroscopy, and electrophoresis measurements. The results show that the complex mainly binds to the double helix of DNA with intercalation mode and the binding constant K is 2.4× 10^4 mol^-1·L. Moreover, the complex can efficiently cleave plasmid DNA at physiological pH and temperature. The cleavage occurs via a hydrolysis mechanism, which is showed by adding radical scavengers, rigorously anaerobic experiments, analysis for malondialdehyde-like products, and the hydrolysis experiment of BDNPP with a rate constant kobs of 5.3 × 10^- 6 s^- 1.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 29771023)the Natural Science Foundation of Shanxi Province
文摘 Hydrolysis of DNA is an important enzymatic reaction , but it is exceedingly difficult to mimic in the laboratory because of the stability of hydrolysis of DNA. In this paper, the cleavage activity of complexes formed between Cu(Ⅱ) and four different amino acid or amino acid methyl ester on DNA is studied by gel elec-trophoresis. It is found that DNA could be cleaved by Cu(Ⅱ)-L-His and Cu(Ⅱ)-L-His methyl ester complexes and the efficiency of cleavage is largely dependent on the metal ion-to-ligand ratio. Further experiments show that the cleavage of DNA mediated by Cu(Ⅱ)-L-His complexes occurs via a hydrolytic mechanism and the active chemical species that affects DNA cleavage is proposed to be MI2H+ and ML2H22+.
文摘The cleavage activity of complexes between copper (Ⅱ) and four different amino acidor amino acid methyl ester on DNA was tested at physioloical pH and temperature., It was found that Cu (Ⅱ)-L-His and Cu (Ⅱ)-L-His methyl ester complexes could cleane DNA. The extent ofDNA cleavage is largely dependent on the metal ion-to-ligand ratio. The cleavage of doublestranded DNA mediated by Cu (Ⅱ)-L-His complexes occurs via a hydrolytie mechanism.
文摘The reaction of bis-[2-amino-4-pheny1-5-thiazolyl] disulfide with 5-nitro-salicylaldehyde in absolute ethanol resulted in the formation of a new Schiff base ligand H<sub>2</sub>L (1). Characterization of the ligand was performed by FT-IR, <sup>1</sup>H NMR, <sup>13</sup>C NMR, UV-Vis, elemental analysis and single crystal X-ray diffraction. The ligand, (1), possesses a disulfide –S–S– bridge of 2.1121 (3) ? length, and the molecule adopts a cis-conformation around this bond. In the crystal structure of (1), an intramolecular O–H···N hydrogen bond with D… A distance of 2.69 (3) ? was present. The reaction of (1) with Co(NO<sub>3</sub>)<sub>2</sub>·6H<sub>2</sub>O and CuCl<sub>2</sub>·2H<sub>2</sub>O in methanol afforded the corresponding metal complexes. The obtained solids were further investigated by elemental analysis and UV-Vis titration that confirmed the formation of [CoL] and [ClCuHL] complexes. However, recrystallizaion of the Co(II) complex in dimethylsulfoxide caused the complete hydrolysis of the imine bond and afforded a Co(II) complex in which two 5-nitro-salicylaldehyde and two DMSO molecules were coordinated to the central metal in an octahedral fashion. This structure (2) was also confirmed by single crystal X-ray analysis.
文摘The electrospray ionization mass spectrometry and tandem mass spectrometry investigation showed that the binding sites of Zn^2＋ with oxidized insulin B chain are His 5, His 10, and Arg 22, which lead to the selective cleavages of the peptide bonds at Ash 3- Gin 4, His 5-Leu 6, Gly 8-Ser 9, and Glu 21-Arg 22 of oxidized insulin B chain.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 29871017 and 29823001)Natural Science Foundation of Jiangsu Province (Grant No. BK97015)
文摘The interaction of oxidized insulin B chain (B) with cis-[Pd(en)Cl2] (en=ethylenediamine), cis-[Pd-(dtco-3-OH)Cl2] (dtco-3-OH= dithiacyclooctan-3-ol) and CuCl2 was studied by electrospray mass spectrometry. It is discovered that the binding of Pd(II) complexes and the sites of cleavage are highly dependent on the secondary structure and local environment of B. The hydrolytic cleavage of denatured B by Pd(II) complexes was monitored by HPLC. The reaction is regioselective and follows first order kinetics with half-life of 4.8 days at 40oC. Two amide bonds, i. e. at Leu6-Cys7 and at Gly8-Ser9, which are dose to the two potential Pd(II) binding sites His5 and His10, are selectively cleaved. In the case of Cu(II) ion as promoter, only one cleavage site was observed which is located at Gly8-Ser9 bond. These results provide improved understanding on the design of artificial metallopeptidase.
文摘A new binuclear complex [Cu2L(OH)](ClO4)3·2H2O has been synthesized and characterized, where L=2,6-bis{[bis-(2-aminoethyl)amino]methyl}-benzene. In the presence of 0.5 mmol/L complex at pH 8.10 and 37°C, the complex can efficiently cleavage pBR322 DNA with a rate constant kobs of 1.35×10-4 s-1. The cleavage occurred by a non-oxidative mechanism showing activity to be dependent on pH.
文摘The electrospray ionization mass spectrometry investigation showed that the binding sites of [ZnL]^2＋, where L is 2-[bis（2- aminoethyl）amino]ethanol, with oxidized insulin B chain are Phel, His5 and Arg22, which lead to the selective cleavages of the peptide bonds at Phe1-Val2, His5-Leu6, Glu21-Arg22, and Arg22-Gly23 of oxidized insulin B chain.
基金Project supported by the National Natural Science Foundation of China （No. 30470408） and Shanxi Provincial Natural Science Foundation.
文摘The complex of Zn[（phen）（dione）Cl]ClO4·H2O （where phen is 1,10-phenanthroline and dione is 1,10-phenanthroline-5,6-dione） has been synthesized and characterized. The interaction of the complex with DNA was investigated using UV absorption, fluorescence spectroscopy, and electrophoresis measurements. The results show that the complex mainly binds to the double helix of DNA with intercalation mode and the binding constant K is 2.4× 10^4 mol^-1·L. Moreover, the complex can efficiently cleave plasmid DNA at physiological pH and temperature. The cleavage occurs via a hydrolysis mechanism, which is showed by adding radical scavengers, rigorously anaerobic experiments, analysis for malondialdehyde-like products, and the hydrolysis experiment of BDNPP with a rate constant kobs of 5.3 × 10^- 6 s^- 1.
