氨基酸Schiff碱及其金属配合物的抑菌抗癌活性的研究进展

氨基酸Ｓｃｈｉｆｆ碱及其金属配合物具有良好的生理、生物活性,本文就近年来国内外在氨基酸Ｓｃｈｉｆ碱及其金属配合的抑菌抗癌活性的研究进展方面进行了综述     

Amino Acid Antagonist Death in Escherichia coli

Six analogues of amino acids killed corresponding auxotrophs of Escherichia coli. With all but one analogue, protein synthesis was required for lethality.     

Synthesis, crystal structure and action on Escherichia coli by microcalorimetry of copper complexes with 1,10-phenanthroline and amino acid

Copper complexes: [Cu(phen)(L-Ser)(H₂O)Cl] (1), [Cu(phen)(Gly)(H₂O)]Cl·3H₂O (2), [Cu(phen)(L-Ala)(H₂O)]Cl·H₂O (3), [Cu(phen)(L-Phe)(H₂O)]Cl·2.5H₂O (4), Cu(phen)₂Cl₂·6H₂O (5) (phen = 1,10-phenanthroline) were synthesized and characterized. The structure of 1 was characterized by X-ray crystallography and showed in a triclinic system with space group P1, a = 6.8953(15) Å, b = 10.737(2) Å, c = 11.894(3) Å, α = 110.395(3)°, β = 94.183(4)° and γ = 100.540(3)°. The antibacterial activities on Escherichia coli (E. coli) of these five copper complexes and CuCl₂ (6) were investigated by microcalorimetry. By analyzing the obtained metabolic thermogenic data and curves, crucial parameters such as rate constant of bacterial growth (k), half inhibitory concentration (IC₅₀), and generation time (t_G) were determined. All these copper complexes could stimulate the growth of the E. coli at their lower concentration. At their higher concentration they all showed antibacterial action. The inhibition on E. coli was 5 > 1 ≈ 2 ≈ 3 ≈ 4 > 6. And the antibacterial mechanism was discussed preliminarily.     

Ultrastructure of Escherichia coli Depleted of an Amino Acid

Particles accumulating during amino acid starvation of Escherichia coli C600 are described and illustrated.     

Radiation Inhibition of Amino Acid Uptake by Escherichia coli

The inhibition of macromolecular synthesis in Escherichia coli by ionizing radiation has been investigated. The survival of the ability to incorporate arginine, leucine, isoleucine, histidine, uracil, and glucose after various doses of gamma radiation, deuteron and alpha particle bombardment has been measured. All amino acids are incorporated by processes which show the same radiation sensitivity. The sensitivity of uracil corresponds to a volume which is roughly spherical, of radius about 160A, whereas the amino acids possess sensitive regions which are long and thin in character. The uptake of glucose is concerned with a smaller, roughly spherical unit. The possible identification of the radiation-sensitive targets with cellular constituents is discussed. The long thin character observed for amino acids suggests that the sensitive region affected by radiation is an unfolded form of a ribosome, or alternatively a long nucleic acid molecule. For uracil the sensitive region fits with a 70S ribosome, while for glucose a smaller particle would fit the data.     

Polysome Turnover During Amino Acid Starvation in Escherichia coli

The experiments presented in this paper support earlier evidence that ribosomes are released from polysomes when they encounter a codon for which no charged transfer ribonucleic acid is available. However, it is further shown that these ribosomes then reinitiate and resume translation. The size and the level of polysomes during deprival of an amino acid is a function of the frequency with which that particular amino acid appears in cellular proteins. Polysomes from starved cells are more stable than those from growing cells, and, moreover, polysomes from starved relaxed strains are more stable than those from starved stringent strains.     

氨基酸Schiff碱金属配合物的研究进展

本文概述了近年来国内外在氨基酸Ｓｃｈｉｆ碱金属配合物领域的研究进展。简介了它们的合成方法和在金属离子分析、药物化学、生物模拟、氨基酸的合成及拆分上的应用。     

Copper complexes of 1,10-phenanthroline and related compounds as superoxide dismutase mimetics

In a preliminary study we tested CuSO4.5H2O, (Cu(II]2[3,5-diisopropylsalicylate]4.2H2O and a number of copper complexes of substituted 1,10-phenanthrolines for superoxide anion dismutase activity. It appeared that this activity depends on the ligands involved and might be governed by the redox potential of the Cu(I) complex/Cu(II) complex couple. The strong superoxide anion dismutase activity of Cu(II)[DMP]2 complex can be expected considering its high redox potential. Rather surprisingly is the superoxide anion dismutase activity of the Cu(I)[DMP]2 complex since it involves oxidation to Cu(II)[DMP]2 complex. From regression analysis it was established that steric and field effects of the substituents of the investigated phenanthrolines play an important role in SOD activity and therefore it is concluded that complex formation is important for the superoxide dismutase-like activity.     

Synergistic lethal effect between hydrogen peroxide and neocuproine (2,9-dimethyl 1,10-phenanthroline) in Escherichia coli

Despite 2,9-dimethyl 1,10-phenanthroline (NC) has been extensively used as a potential inhibitor of damage due to oxidative stress in biological systems, the incubation of E. coli cultures with the copper ion chelator NC prior to the challenge with hydrogen peroxide caused a lethal synergistic effect. The SOS response seems to be involved in the repair of the synergistic lesions through the recombination pathway. Furthermore, there is evidence for the UvrABC excinuclease participation in the repair of the synergistic lesions, and the base excision repair may also be required for bacterial survival to the synergistic effect mainly at high concentrations of H2O2, being the action of Fpg protein an important event. Incubation of lexA (Ind-) cultures with iron (II) ion chelator 2,2'-dipyridyl simultaneously with NC prevented the lethal synergistic effect. This result suggests an important role of the Fenton reaction on the phenomenon. NC treatment was able to increase the number of DNA strand breaks (DNAsb) induced by 10 mM of H2O2 in lexA (Ind-) strain and the simultaneous treatment with 2,2'-dipyridyl was able to block this effect.     

复合氨基酸铜螯合物的研究

以废弃鸡毛的硫酸水解液作为复合氨基酸的来源 ,将其与CuSO4 ·5H2 O螯合 ,采用有机溶剂沉淀法制取了高纯度的氨基酸铜螯合物 ,并用化学分析和红外光谱分析对其进行了研究 ;同时 ,提出了一种根据直接测定螯合态微量元素的含量来测定螯合率的新方法 ,为螯合率的测定提供了一条新的途径     

Site-specific DNA cleavage of synthetic NarL sites by an engineered Escherichia coli NarL protein-1,10-phenanthroline cleaving agent

The NarL response regulatory protein of Escherichia coli has been engineered by covalent modification with 1,10-phenanthroline (OP) to create a set of site-specific DNA-cleaving agents. This was accomplished by introducing single cysteine amino acid replacements at selected locations within the carboxy-terminal DNA-binding domain in or nearby the helix 8 to helix 9 region of the NarL protein using site-directed mutagenesis. Of 18 modified NarL-OP proteins made, 13 retained the ability to bind DNA as evidenced by gel mobility assays, whereas 10 of the 1,10-phenanthroline-modified proteins also exhibited specific cleavage activity for a synthetic NarL recognition sequence. These DNA-cleaving agents were divided into two groups based on the location of the cleavage sites. The first class set cleaved the DNA nearby the center of a synthetic 7-2-7 sequence composed of two NarL heptamer sites separated by a 2-bp spacer element. The second class cut the DNA at the periphery of the 7-2-7 sequence. The cleavage data are consistent with the ability of two NarL monomers to recognize and bind to the DNA in a head-to-head orientation. A second set of DNA-cleaving agents was constructed using the carboxy-terminal domain of NarL called NarL(C). Similar cleavage patterns were observed whether full-length NarL or NarL(C) was used. The availability of 1,10-phenanthroline-modified NarL and NarL(C) proteins opens up the possibility to explore the position, orientation, and number of NarL recognition sites at E. coli promoters predicted to contain multiple and complex arrangements of NarL-binding sites.     

Studies on Resistance Transfer Factor Deoxyribonucleic Acid in Escherichia coli

A variant of the derepressed R factor, R1, which does not contain any of the drug resistance markers, and represents, in large part, the resistance transfer factor (RTF) was studied in Escherichia coli. RTF deoxyribonucleic acid (DNA) was specifically labeled in a female cell after conjugation. Physical characterization of the molecule showed that RTF possessed an average molecular weight of 50 x 10(6) daltons and a buoyant density of 1.709 g/cm(3). By comparison to R1, we calculate that the region of DNA carrying the drug resistance genes is therefore about 20% of the R1 molecule and has a buoyant density of approximately 1.716 g/cm(3). These results support the hypothesis that the single species of R-factor DNA observed in E. coli represents a composite of the 1.709 and 1.716 g/cm(3) replicons seen in Proteus.     

Amino Acid Control over Deoxyribonucleic Acid Synthesis in Escherichia coli Infected With T-Even Bacteriophage

Starvation for a required amino acid of normal or RC(str)Escherichia coli infected with T-even phages arrests further synthesis of phage deoxyribonucleic acid (DNA). This amino acid control over phage DNA synthesis does not occur in RC(rel)E. coli mutants. Heat inactivation of a temperature-sensitive aminoacyl-transfer ribonucleic acid (RNA) synthetase similarly causes an arrest of phage DNA synthesis in infected cells of RC(str) phenotype but not in cells of RC(rel) phenotype. Inhibition of phage DNA synthesis in amino acid-starved RC(str) host cells can be reversed by addition of chloramphenicol to the culture. Thus, the general features of amino acid control over T-even phage DNA synthesis are entirely analogous to those known for amino acid control over net RNA synthesis of uninfected bacteria. This analogy shows that the bacterial rel locus controls a wider range of macromolecular syntheses than had been previously thought.     

Basic Amino Acid Transport in Escherichia coli: Properties of Canavanine-Resistant Mutants

A mutant of Escherichia coli strain CanR 22 has been isolated which is resistant to growth inhibition by canavanine, an analogue of arginine. The properties of this strain and of another canavanine-resistant mutant, JC182-5 (isolated by Celis et al. [5]), were studied. The mutation is pleiotropic in that it results in a reduction in the activity of two distinct permeases, the arginine-specific and lysine-arginine-ornithine transport systems. The lesion maps at min 56 of the E. coli linkage map, at or near the argP locus. Although strain CanR 22 excretes arginine, this excretion appears to result from reduced ability to concentrate arginine, rather than the loss of transport ability being the result of excretion. This conclusion is based on findings with a canavanine-resistant strain auxotrophic for arginine, which exhibits transport properties similar to those of the prototrophic strains. Additionally, growth in the presence of arginine or ornithine results in a repression of the activity of the two basic amino acid transport systems. Neither the arginine-specific nor the lysine-arginine-ornithine binding proteins of the mutant cells show significant alterations in terms of amount, physical properties, or kinetic parameters. These observations lead to the proposal of a model for the two basic amino acid transport systems in which two carrier proteins with different specificities interact with a common energy coupling mechanism. A lesion in the gene (or one of the genes) for this coupling mechanism can confer canavanine resistance.     

Inhibitory Effect of Diphtheria Toxin on Amino Acid Incorporation in Escherichia coli Cell-Free System

The mechanism of action of diphtheria toxin in an Escherichia coli cell-free protein-synthesizing system was examined. When the washed ribosomes were incubated with toxin before addition of messenger ribonucleic acid (RNA), peptide syntheses of (14)C-phenylalanine directed by polyuridylic acid or phage R17 RNA were strongly inhibited by a small amount of toxin. Whereas, if the soluble fraction (105,000 x g supernatant fraction) was preincubated with toxin, no effect of toxin occurred either on the induced protein synthesis or on the activity of guanosine triphosphatase even in the presence of nicotinamide adenine dinucleotide. The binding of (3)H-formylmethionyl-transfer RNA to E. coli ribosomes directed by either R17 RNA or trinucleotide AUG was also decreased by toxin. These findings suggest that diphtheria toxin may prevent the binding of messenger RNA by successfully competing with the AUG for ribosomal binding sites. Sucrose-density gradient studies support this concept by showing the decrease in binding of (3)H-labeled R17 RNA to E. coli ribosomes exposed to toxin.     

Inhibition of E. coli DNA polymerase I by 1,10-phenanthroline.

A 1,10-phenanthroline-cuprous ion complex is a potent reversible inhibitor of $\text{E. coli}$ DNA polymerase I yielding 50% inhibition in the micromolar concentration range. The 2:1 1,10-phenanthroline-cuprous ion complex is most probably the inhibitory species. Complexes of cupric ion and 1,10-phenanthroline have no apparent kinetic effect. The previously reported inhibition of the enzyme by 1,10-phenanthroline (1,2) is most likely due to the formation of this complex from thiols normally added to the assay mixtures and trace amounts of cupric ion invariably present notwithstanding reasonable precaution. The reversible and instantaneous 1,10-phenanthroline inhibition observed for other polymerases may be due to this unique inhibitory species and not coordination of a catalytically important zinc ion at the active site by the chelating agent.