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1.
Haroun M Ravelet C Ravel A Grosset C Villet A Peyrin E 《Journal of separation science》2005,28(5):409-420
The D-, L-tryptophan binding and the chiral recognition properties of the teicoplanin and teicoplanin aglycone (TAG) chiral stationary phase (CSPs) were compared at various column temperatures. The solute adsorption isotherms (bi-Langmuir model) were determined for both the two CSPs using the perturbation method. It was demonstrated that the sugar units were involved in the reduction of the apparent enantioselectivity through two phenomena: (i) the inhibition of some enantioselective contacts with low-affinity binding regions of the aglycone and (ii) a decrease in the stereoselective properties of the aglycone high-affinity binding pocket. The phenomenon (ii) was governed by both a decrease in the ratio of the enantiomer adsorption constant and a strong reduction of the site accessibility for D- and L-tryptophan. In addition, a temperature effect study was performed to investigate the chiral recognition mechanism at the aglycone high-affinity pocket. An enthalpy-entropy compensation analysis derived from the Grunwald model as well as the comparison with the literature data demonstrated that the enantioselective binding mode was dependent on an interface dehydration process. The change in the enantioselective process observed between the TAG and teicoplanin CSP was characterized by a difference of ca. 2-3 ordered water molecules released from the species interface. 相似文献
2.
This work utilizes on-column ligand synthesis and affinity capillary electrophoresis (ACE) to determine binding constants (Kb) of 9-flourenylmethyloxy carbonyl (Fmoc)-amino acid derivatives to the glycopeptide antibiotics ristocetin (Rist) and teicoplanin (Teic). In this technique, two separate plugs of sample are injected on to the capillary column and electrophoresed. The initial sample plug contains a d-Ala-d-Ala terminus peptide and either one or two non-interacting standard(s). The second plug contains a Fmoc-amino acid-N-hydroxysuccinimide (NHS) ester. The electrophoresis is then carried out with an increasing concentration of Rist or Teic in the running buffer. Upon electrophoresis the initial d-Ala-d-Ala peptide reacts with the Fmoc-amino acid yielding a new Fmoc-amino acid-d-Ala-d-Ala peptide derivative. Continued electrophoresis results in the binding of Rist or Teic to the Fmoc-amino acid-d-Ala-d-Ala peptide derivatives. Analysis of the change in the relative migration time ratio (RMTR) or electrophoretic mobility () of the Fmoc-amino acid-d-Ala-d-Ala peptide derivatives relative to the non-interacting standards, as a function of the concentration of Rist and Teic, yields a value for
Kb. These findings demonstrate the advantage of coupling on-column ligand synthesis to ACE for estimating binding parameters between antibiotics and ligands.Abbreviations Rist
Ristocetin
- Teic
Teicoplanin
- ACE
Affinity capillary electrophoresis
- RMTR
Relative migration time ratio 相似文献
3.
Binding constants between the glycopeptides teicoplanin (Teic) and ristocetin (Rist) and their derivatives to D-Ala-D-Ala terminus peptides were determined by on-column receptor synthesis coupled to partial-filling affinity capillary electrophoresis (PFACE) or affinity capillary electrophoresis (ACE). In these techniques, the column is first partially filled with increasing concentrations of D-Ala-D-Ala terminus peptides. This is followed by plugs of buffer, antibiotic and two noninteracting standards, and acetic and/or succinic anhydride (and buffer in the case of ACE). The order of the reagent plugs containing the antibiotic and anhydride varies with the charge of the glycopeptide. Upon electrophoresis, the antibiotic reacts with the anhydride yielding a derivative of Teic or Rist. Continued electrophoresis results in the overlap of the derivatized antibiotic and the plug of D-Ala-D-Ala peptide. Analysis of the change in the relative migration time ratio (RMTR) of the new glycopeptide relative to the standards, as a function of the concentration of the D-Ala-D-Ala ligand yields a value for the binding constant K(b). The techniques described here can be used to assess how the derivatization of drugs alters their affinities for target molecules. 相似文献
4.
Food allergen detection methods and the challenge to protect food-allergic consumers 总被引:1,自引:0,他引:1
van Hengel AJ 《Analytical and bioanalytical chemistry》2007,389(1):111-118
The detection of allergenic ingredients in food products has received increased attention from the food industry and legislative
and regulatory agencies over recent years. This has resulted in the improvement of measures aimed at the protection of food-allergic
consumers. The controlled production of food products and control activities executed by food inspection agencies rely on
the availability of methods capable of detecting traces of allergenic ingredients. The development of such methods faces a
multitude of analytical challenges. Those challenges will be identified and discussed in this review. Furthermore, future
developments and trends in analytical methodology as applied to the detection of food allergens are reported. 相似文献
5.
6.
McCarthy EL Egeler TJ Bickerstaff LE Pereira da Cunha M Millard PJ 《Analytical and bioanalytical chemistry》2006,386(7-8):1975-1984
Unique base sequences derived from RNA of both infectious hematopoietic necrosis virus (IHNV) and infectious salmon anemia
virus (ISAV) were detected and identified using a combination of surface-associated molecular padlock DNA probes (MPPs) and
rolling circle amplification (RCA) in microcapillary tubes. DNA oligonucleotides with base sequences identical to RNA obtained
from IHNV or ISAV were recognized by MPPs. Circularized MPPs were then captured on the inner surfaces of glass microcapillary
tubes by immobilized DNA oligonucleotide primers. Extension of the immobilized primers by isothermal RCA produced DNA concatamers,
which were labeled with fluorescent SYBR Green II nucleic acid stain, and measured by microfluorimetry. Molecular padlock
probes, combined with this method of surface-associated isothermal RCA, exhibited high selectivity without the need for thermal
cycling. This method is applicable to the design of low-power field sensors capable of multiplex detection of viral, bacterial,
and protozoan pathogens within localized regions of microcapillary tubes.
相似文献
7.
8.
Gratacós-Cubarsí M García-Regueiro JA Castellari M 《Analytical and bioanalytical chemistry》2007,387(6):1991-1998
Enrofloxacin is a synthetic bacteriostatic administered in veterinary therapy. It can also be used illegally as a growth promoter
to enhance feed efficiency and weight gain. This practice is banned in several countries due to its potential negative effects
on the environment and human health. A suitable method for extracting and quantifying enrofloxacin (ENR) and its main metabolite
ciprofloxacin (CPR) in cattle and pig hair by high-performance liquid chromatography–fluorimetric detection (HPLC–FLD) had
been proposed. ENR and CPR were extracted from hair samples with methanol acidified with trifluoroacetic acid for 24 h at
70 °C. The extracts were evaporated and redissolved in the mobile phase before injection. This simplified procedure enabled
the detection of both CPR and ENR at ng g−1 levels (limit of detection 4–5 ng g−1) without further purification. Detectable residues of ENR were found in calf and pig hairs after the pharmacological treatment
was started. Mean concentrations of quinolone (ENR, CPR) in contaminated hairs ranged from 20 to 2,518 ng g−1 in calves and from 152 to 1,140 ng g−1 in pigs. Hair pigmentation enhanced quinolone accumulation significantly. Hair analysis seems to increase the time window
available for the retrospective detection of illegal ENR administration compared to edible tissue analysis. 相似文献
9.
磁性壳聚糖-聚丙烯酸微球的制备及表征 总被引:12,自引:0,他引:12
壳聚糖通过与丙烯酸接枝共聚制得壳聚糖聚丙烯酸悬浮液,在铁磁流体(Fe3O4)与聚乙二醇(分散剂)存在下通过与戊二醛交联,制备了磁性壳聚糖聚丙烯酸微球。用扫描电镜、红外光谱对合成的高分子微球进行形貌观察和结构表征,并进行了元素分析和磁性能测试,研究了磁性微球对牛血清白蛋白(BSA)的吸附效果。结果表明,合成的磁性微球外表呈球形,粒径为100~400nm;当Fe含量为2.47%时,磁性微球的饱和磁化强度约为1.30emug,磁矫顽力为280Oe,磁化率为2.16×10-4(常温下),属于顺磁性材料;其对BSA有较好的吸附效果,饱和吸附量约为400mgg。 相似文献
10.
In this paper, two chiral stationary phases were prepared by coating the surface of both C8 and C18 high-performance liquid chromatography (HPLC) supports with the teicoplanin chiral selector. The hydrophobic C11 acyl side chain, attached to the d-glucosamine group of teicoplanin, served as anchor moiety for the immobilization of the chiral selector on the apolar support material. The retention and enantioselectivity of these coated stationary phases were studied using some aromatic amino acids as probe solutes and an aqueous solution as mobile phase. It was found that the enantiomer elution order on the modified C8 and C18 stationary phases was reversed (l > d) relatively to that classically observed with a teicoplanin covalently immobilized on a silica support (d > l). Such a dynamic coating on the reversed-phase supports was found to be of interest since the apparent enantioselectivity was not significantly changed by the use during an extended period of time or following a long-term storage of the columns. 相似文献
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12.
含羟基磁性高分子微球的合成及表征 总被引:14,自引:0,他引:14
采用分散聚合法,以Fe3O4粉末为磁核,苯乙烯-甲基丙烯酸羟乙酯共聚物为高分子壳层、合成了带羟基的磁性复合高分子微球。Fe3O4与苯乙烯等油溶性单体亲合性差,有聚乙二醇溶液处理磁粉增强其表面亲水、亲油性。控制合成条件,成可以得到粒径为50-500μmFe3O4含量为0.5-2.5%的磁性微球。 相似文献
13.
荧光磁性双功能树状分子微球的制备与表征 总被引:1,自引:0,他引:1
采用化学共沉淀法, 以FeCl3·6H2O和FeSO4·7H2O为原料制备了磁性Fe3O4纳米颗粒, 采用树状大分子对其进行修饰, 然后通过树状大分子具有的大量空腔及末端丰富的氨基, 经吸附、 键合, 与大量巯基乙酸修饰的CdSe/CdS量子点连接, 得到三代具有荧光磁性双功能的树状分子微球, 并对其进行结构表征与性能测试. 结果表明: 三代复合后的微球的平均粒径分别为15, 34和49 nm; 一代荧光磁性微球的发光性能最佳, 其量子产率达24.1%; 零代荧光磁性微球磁性能最优, 其饱和磁化强度为15.96 A·m2/kg. 这种具有荧光和磁性的双功能纳米复合微粒有望在免疫检测、 靶向治疗、 荧光追踪和磁性分离等方面得到广泛应用. 相似文献
14.
本文设计并合成了良好水溶性的赖氨酸修饰壳聚糖,并对制备工艺进行了优化.产物通过红外(FTIR)和核磁(1H-NMR)进行了表征,并将其作为壳层材料制备了赖氨酸修饰壳聚糖磁性超微载体.通过光电能谱(XPS)、透射(TEM)、激光粒度仪、X射线衍射(XRD)、磁性能测试(VSM)对载体进行了表征.结果表明,制备的赖氨酸修饰壳聚糖磁性超微载体表面带有大量的氨基(-NH2),粒径分布较为均一(100nm左右),形貌较为规则,并具有良好的超顺磁性,因而该载体具有更加良好的性能. 相似文献
15.
Karen Kennedy Miroslava Macova Frederic Leusch Michael E. Bartkow Darryl W. Hawker Bin Zhao Michael S. Denison Jochen F. Mueller 《Analytical and bioanalytical chemistry》2009,394(5):1413-1421
Passive air sampling was undertaken using polyurethane foam passive air samplers at three types of locations, including indoors
(six offices) at buildings in the central business district (CBD) and at a private suburban home (indoor and outdoor) located
9 km from the CBD in Brisbane, Queensland, Australia. Estrogenic (E-SCREEN—MCF7-BOS) and aryl hydrocarbon receptor (AhR) (CAFLUX—H4G1.1c2)
activity were assessed for samples collected from each of these locations. The samples were tested either as crude extracts
(“untreated”) or were subjected to H2SO4 silica gel (“treated”) for each location in order to determine whether chemicals, which are not resistant to this treatment
like polycyclic aromatic hydrocarbons, potentially account for the observed activity. In most cases, H2SO4 treatment resulted in a statistically significant reduction of potency for both endpoints, suggesting that chemicals less
resistant to treatment may be responsible for much of the detected biological activity in these locations. Estrogenic potency
measurements (<0.22–185 pg m−3) were highest in the indoor offices, followed by the indoor suburban home and finally the outdoor suburban home (which was
not estrogenic). Total AhR activity for crude extracts (1.3–10 pg m−3) however was highest for the outdoor suburban home site. Levels of polycyclic aromatic hydrocarbons were monitored indoors
and outdoors at the suburban home. At that location, polycyclic aromatic hydrocarbon air concentrations were on average approximately
two times higher outdoor than indoor, while AhR potency was five times higher outdoor than indoor. No significant correlation
was found between the estrogenic and AhR activity (P = 0.88) for the sites in this study.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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17.
Use of Magnetic Nanoparticles and a Microplate Reader with Fluorescence Detection to Detect C‐reactive Protein 下载免费PDF全文
Two approaches based on magnetic nanoparticles (MNPs) have been compared to analyze C‐reactive protein (CRP). Both the non‐eluted and eluted MNP‐1°Ab‐CRP‐2°Ab/FITC bioconjugates were measured by a microplate reader with fluorescence detection. The linear ranges for the non‐elution and elution methods were 10‐200 and 0.1‐2.0 μg/mL, respectively. The concentration limits of detection for the nonelution and elution methods were 2.91 and 0.04 μg/mL, respectively. The non‐ elution method gave better precision and recovery than the elution method, and also showed comparable results to that of ELISA assay. The non‐elution method is simple and only needs minute volumes of sample and buffer. There is no need to dissociate the fluorescence probes from the bioconjugates, and the fluorescence signals can be directly measured on the MNP‐1°Ab‐CRP‐2°Ab/FITC bioconjugates. Meanwhile, samples with high CRP concentrations are not necessarily to be diluted before analysis. 相似文献
18.
In-hospital deaths caused by the infection of methicillin-resistant Staphylococcus aureus (MRSA) are on the increase worldwide. Teicoplanin is a potent glycopeptide antibiotic against MRSA. A rapid and cost-saving micellar electrokinetic chromatography (MEKC) method combined with solid phase extraction (SPE) was developed and then validated to quantify teicoplanin in patient serum in this work. The method includes the following steps: (1) pretreatment of the serum samples with 10 M urea to denature proteins, (2) application of SPE by using an OASIS HLB cartridge to clean up and concentrate the serum samples, and (3) use of MEKC for sample analysis. Under the optimized conditions, the SPE recovery of teicoplanin is higher than 90%. The six major components of teicoplanin could be baseline-separated from one another and endogenous materials in 12 min with a background electrolyte composed of 20 mM sodium tetraborate buffer pH 8.8, 40 mM sodium dodecyl sulfate, and 11% (v/v) ACN. The relative standard deviation (R.S.D.) of the peak area ratios for method repeatability (n = 6) and intermediate precision (inter-day, n = 3) were found to be lower than 4.18% and 5.30%, respectively. The calibration curves were linear between the chromatographic response and total teicoplanin concentration over the range of 5 μg/mL to 55 μg/mL. Limit of detection (LOD) for each of the six components was found to be lower than 0.06 μg/mL. Pearson’s correlation revealed that a good correlation (r = 0.98) was obtained between the SPE-MEKC method and the fluorescence polarization immunoassay (FPIA) method. The developed method can be used to quantitatively determine serum teicoplanin concentration in patients for dose monitoring and clinical research. 相似文献
19.
E. Renault M.P. Fontaine-Aupart F. Tfibel M. Gardes-Albert M. Gardes-Albert E. Bisagni 《Journal of photochemistry and photobiology. B, Biology》1997,40(3):218-227
The antitumor drug pazelliptine (PZE) binds to natural and synthetic DNA sequences at 100 mM NaCl, pH 7.0, as deduced from the absorption and fluorescence data. Scatchard plots constructed from the results obtained with poly(dG-dC)-poly(dG-dC) give binding constants of base pairs in the range (2–6) × 105 M−1. The modifications in the absorption and fluorescence spectra observed when PZE binds to various polynucleotides, namely poly(dA-dT)-poly(dA-dT), poly(dA)-poly(dT), poly(dG-dC)-poly(dG-dC) and calf thymus DNA. reveal a change in the protonation state of the drug upon binding, increasing the apparent pKa of its 9-N nitrogen atom. The PZE excited state properties serve as a sensitive probe to distinguish between homo and hetero A-T sites as well as between AT and GC sites. Fluorescence studies reveal that energy transfer occurs from polynucleotide bases to the bound PZE chromophore, a result consistent with an intercalative mode of binding of the drug to DNA. The emission is enhanced when PZE is bound to A-T base pairs ( 30% increase of φF) whereas it is quenched in the vicinity of G-C base pairs ( 90% decrease of φF). Furthermore, the fluorescence spectrum obtained with calf thymus DNA is hardly distinguishable from that obtained with poly(dG-dC)-polu(dG-dC), suggesting a binding of PZE to G-C rich regions. 相似文献
20.
Wang Z Li D Jin J 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,70(4):866-870
The interaction between lysozyme (LYSO) and puerarin has been studied at three temperatures (294, 302 and 310K) through/using fluorescence spectroscopy and circular dichroism (CD). The LYSO fluorescence was quenched by the binding of puerarin to LYSO. The binding constants and the number of binding sites can be calculated from the data obtained from fluorescence quenching experiments. According to the van't Hoff equation, the standard enthalpy change (DeltaH degrees ) and standard entropy change (DeltaS degrees ) for the reaction were calculated to be 17.47kJ/mol and 163.5J/molK. It indicated that the hydrophobic interactions play a main role in the binding of puerarin to LYSO. In addition, the distance between puerarin (acceptor) and tryptophan residues of LYSO (donor) was estimated to be 1.47nm on the basis of fluorescence energy transfer. The changes of LYSO secondary structure in the presence of puerarin were observed from CD spectroscopy. 相似文献