氨基化镁铝类水滑石修饰电极及电化学杀菌

以层间插入十二烷基磺酸钠的镁铝类水滑石（Mg/Al-SDS-HTLc）,与十六烷基三甲基溴化铵（CTAB）和3-氨丙基三乙氧基硅烷（APS）缩合反应制备了氨基化镁铝类水滑石（Mg/Al-NH2-HTLc）。 然后以Mg/Al-NH2-HTLc修饰热解石墨电极,通过循环伏安法探讨了该电极对吸附在其表面的大肠杆菌的杀灭作用。 结果表明,被吸附的大肠杆菌在经过循环伏安扫描后死亡率达到98.68%,大肠杆菌的死亡可能是由于细胞膜中易氧化物质（如鸟嘌呤）被氧化所致。     

大肠杆菌HB101感受态细胞的显微观察与分析

对数生长前期的大肠杆菌在生理盐水中用CaCl2可以直接诱导建立感受态并完成转化过程。利用H－8100透射电子显微镜观察用CaCl2直接在生理盐水中诱导建立感受态的大肠杆菌细胞，发现感受态细胞整体电子密度趋于均匀，但存在有电子密度较高颗粒，表明大肠杆菌感受态建立过程中，细胞整体对电子通透性增强，可能存在涉及细胞膜通透性的复合物重新形成相关的胞内物质代谢及其在细胞内定位的受控改变，暗示大肠杆菌可能具有建立自然感受态的能力。     

Synthesis,cytotoxicity and antibacterial studies of symmetrically and non‐symmetrically benzyl‐ or p‐cyanobenzyl‐substituted N‐Heterocyclic carbene–silver complexes

From the reaction of 1H‐imidazole ( 1a ), 4,5‐dichloro‐1H‐imidazole ( 1b ) and 1H‐benzimidazole ( 1c ) with p‐cyanobenzyl bromide ( 2 ), symmetrically substituted N‐heterocyclic carbene (NHC) [( 3a–c )] precursors, 1‐methylimidazole ( 5a ), 4,5‐dichloro‐1‐methylimidazole ( 5b ) and 1‐methylbenzimidazole ( 5c ) with benzyl bromide ( 6 ), non‐symmetrically substituted N‐heterocyclic carbene (NHC) [( 7a–c )] precursors were synthesized. These NHC? precursors were then reacted with silver(I) acetate to yield the NHC‐silver complexes [1,3‐bis(4‐cyanobenzyl)imidazole‐2‐ylidene] silver(I) acetate ( 4a ), [4,5‐dichloro‐1,3‐bis(4‐cyanobenzyl)imidazole‐2‐ylidene] silver(I) acetate ( 4b ), [1,3‐bis(4‐cyanobenzyl)benzimidazole‐2‐ylidene] silver(I) acetate ( 4c ), (1‐methyl‐3‐benzylimidazole‐2‐ylidene) silver(I) acetate ( 8a ), (4,5‐dichloro‐1‐methyl‐3‐benzylimidazole‐2‐ylidene) silver(I) acetate ( 8b ) and (1‐methyl‐3‐benzylbenzimidazole‐2‐ylidene) silver(I) acetate ( 8c ) respectively. The four NHC‐precursors 3a–c, 7c and four NHC–silver complexes 4a–c and 8c were characterized by single crystal X‐ray diffraction. The preliminary antibacterial activity of all the compounds was studied against Gram‐negative bacteria Escherichia coli, and Gram‐positive bacteria Staphylococcus aureus using the qualitative Kirby‐Bauer disc‐diffusion method. All NHC–silver complexes exhibited medium to high antibacterial activity with areas of clearance ranging from 4 to 12 mm at the highest amount used, while the NHC‐precursors showed significantly lower activity. In addition, all NHC–silver complexes underwent preliminary cytotoxicity tests on the human renal‐cancer cell line Caki‐1 and showed medium to high cytotoxicity with IC₅₀ values ranging from 53 ( ± 8) to 3.2 ( ± 0.6) µM. Copyright © 2010 John Wiley & Sons, Ltd.     

Microcalorimetric Character of Inhibition of Salicylaldehyde Glucosamine Schiff Base SG on Bacterial Metabolism

ＩｎｔｒｏｄｕｃｔｉｏｎＳｉｎｃｅＳｃｈｉｆｂａｓｅａｎｄｉｔｓｍｅｔａｌｃｏｍｐｌｅｘｅｓａｒｅｏｆａｎｔｉｂａｃｔｅｒｉａｌａｎｄａｎｔｉｃａｎｃｅｒｂｉｏａｃｔｉｖｉｔｉｅｓ，ｔｈｅｙｈａｖｅｂｅｅｎａｒｅｓｅａｒｃｈｓｕｂｊｅｃｔｏｆｍｕｃｈ...     

具有真细菌基因启动子活性的古生菌DNA片段

以大肠杆菌启动子探测质粒pKK232-8 为载体,用4 组限制性内切酶分别消化古生菌盐生盐杆菌R1(Halobacterium halobium )的染色体DNA,在体外进行重组,转化E.coliDH-5α感受态细胞,得到12 个转化子(T1～T12),其抗性水平分布在10～500 m g/L的区间内. 将这些转化子所含质粒分别命名为pSX1～pSX12,限制性酶切分析表明,这些质粒各插入了一段不同的外源DNA 片段,杂交分析表明,抗性最强的转化子T11 所含质粒pSX11 上插入了一段来源于盐生盐杆菌R1 染色体的DNA 片段. 该DNA 片段在大肠杆菌中具有启动子功能.     

Investigation of the Effect of Four Organic Acids in Radix Isatidis on E. coli Growth by Microcalorimetry

The inhibitory effects of four organic acids (OAs) in Radix Isatidis, a traditional Chinese medicinal herb, on Escherichia coli (E. coli) growth were investigated by microcalorimetry. The power‐time curves of E. coli growth with and without OAs were acquired, meanwhile the extent and duration of inhibitory effects on the metabolism were evaluated by growth rate constants (k₁, k₂), half inhibitory ratio (IC₅₀), maximum heat output (P_max) and peak time (t_p). The values of k₁ and k₂ of E. coli growth in the presence of the four OAs decreased with the increasing concentrations of OAs. Moreover, P_max was reduced and the value of t_p increased with increasing concentrations of the four drugs. The sequence of anti‐microbial activity of the four OAs was: syringic acid>2‐amino‐benzoic acid>salicylic acid>benzoic acid. IC₅₀ of the four OAs was respectively 56 µg/mL for syringic acid, 75 µg/mL for 2‐amino‐benzoic acid, 86 µg/mL for salicylic acid and 224 µg/mL for benzoic acid. The existence of the functional groups on phenyl ring improves the anti‐microbial activity compared to benzoic acid. The functional groups methoxyl at C(3) and C(5) improve anti‐microbial activity more strongly than the other functional groups, and the functional group amino at C(2) improve anti‐microbial activity more strongly than hydroxyl at C(2) on phenyl ring.     

Analysis of E. coli soluble proteins by non‐denaturing micro 2‐DE/3‐DE and MALDI‐MS‐PMF

Escherichia coli (strain K‐12)‐soluble proteins were analyzed by nondenaturing micro 2‐DE and MALDI‐MS‐PMF. The reported conditions of nondenaturing IEF in agarose column gels [Jin, Y., Manabe, T., Electrophoresis 2009, 30, 939–948] were modified to optimize the resolution of cellular soluble proteins. About 300 CBB‐stained spots, the apparent molecular masses of which ranged from ca. 6000 to 10 kDa, were detected. All the spots on two reference 2‐DE gels (one for wide mass range and one for low‐molecular‐mass range) were numbered and subjected to MALDI‐MS‐PMF for the assignment of constituting polypeptides. Most of the spots (310 spots out of 329) provided significant match (p<0.05) with polypeptides in Swiss‐Prot database and totally 228 polypeptide species were assigned. Activity staining of enzymes such as alkaline phosphatase and catalases was performed on the 2‐DE gels and the locations of the activity spots matched well with those of the MS‐assigned polypeptides of the enzymes. Most of the polypeptides with subunit information in Swiss‐Prot (119 polypeptides as homo‐multimers and 25 as hetero‐multimers out of the 228), such as pyruvate dehydrogenase complex which is composed of three enzymatic components, were detected at the apparent mass positions of their polymers, suggesting that the proteins were separated retaining their subunit structures. When a nondenaturing 2‐DE gel was vertically cut into 2 mm strips and one of the strips was subjected to a third‐dimension micro SDS‐PAGE (micro 3‐DE), about 190 CBB‐stained spots were detected. The assignment of the polypeptides separated on the 3‐DE gel would further provide information on protein/polypeptide interactions.     

Chemical Evolution of a Bacterial Proteome

We have changed the amino acid set of the genetic code of Escherichia coli by evolving cultures capable of growing on the synthetic noncanonical amino acid L ‐β‐(thieno[3,2‐b]pyrrolyl)alanine ([3,2]Tpa) as a sole surrogate for the canonical amino acid L ‐tryptophan (Trp). A long‐term cultivation experiment in defined synthetic media resulted in the evolution of cells capable of surviving Trp→[3,2]Tpa substitutions in their proteomes in response to the 20 899 TGG codons of the E. coli W3110 genome. These evolved bacteria with new‐to‐nature amino acid composition showed robust growth in the complete absence of Trp. Our experimental results illustrate an approach for the evolution of synthetic cells with alternative biochemical building blocks.     

高效液相色谱-串联质谱法分析大肠杆菌代谢组中样品提取方法的比较

比较了基于液相色谱和串联质谱联用技术(LC-MS/MS)的Ecoli代谢组分析的5种不同样品提取方法.在对样品进行淬灭和洗涤后,分别使用冷甲醇法、热乙醇法、甲醇/氯仿法、热甲醇法和高氯酸法对样品平行提取3次,每个样品重复进样3次.结果显示,冷甲醇法所得到的相对提取率最高,且重复性好(RSD<5%).从相对提取率、重复性...     

Single‐Cell Investigations of Silver Nanoparticle–Bacteria Interactions

Interaction of bacteria with citrate‐reduced silver nanoparticles (AgNPs) of size 25 nm ± 8.5 nm is studied using Raman spectroscopy in conjunction with plasmon resonance imaging of single bacterial cells. Distribution of isolated nanoparticles (NPs) inside Escherichia coli (ATCC 25922; E. coli) is observed by hyperspectral imaging (HSI) as a function of incubation time. Time‐dependent degradation of bacterial DNA upon incubation of AgNPs with E. coli is proven by Raman spectroscopic studies. While attachment of NPs is evident in HSI, molecular changes are evident from the surface‐enhanced Raman spectra of adsorbed DNA and its fragments. Distinct enhancement of DNA features is observed upon interaction of AgNPs and the number of such distinct features increases with incubation time, reaches a maximum, and decreases afterwards. This systematic interaction of DNA with the NPs system and its gradual chemical evolution is proven by investigating isolated plasmid DNA. A comparative Raman study with silver ions has shown that DNA features are observable only when bacteria are incubated with AgNPs. Energetics of interaction examined with microcalorimetry suggests the exothermicity of ?1.547 × 10¹⁰ cal mol^?1 for the NP–bacteria system. Specific interaction of AgNPs with exocyclic nitrogen present in the bases, adenine, guanine, and cytosine, leads to the changes in DNA.