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101.
Hervé Poras Rémi Patouret Simon Leiris Tanja Ouimet Marie-Claude Fournié-Zaluski Bernard P. Roques 《Bioorganic & medicinal chemistry letters》2017,27(16):3883-3890
New neprilysin inhibitors containing an α-mercaptoketone HSC(R1R2)CO group, as zinc ligand were designed. Two parameters were explored for potency optimization: the size of the inhibitor which could interact with the S1, S1′ or S2′ domain of the enzyme and the nature of the substituents R1, R2 of the mercaptoketone group. Introduction of a cyclohexyl chain in R1, R2 position and a (3-thiophen)benzyl group in position R3 (compound 12n) yielded to the most potent inhibitor of this series with a Ki value of 2 ± 0.3 nM. This result suggests that this new inhibitor interacts within the S1, S1′ domain of NEP allowing a pentacoordination of the catalytic Zn2+ ion by the mercaptoketone moiety. 相似文献
102.
Olga Berejnaia Hao WangMarc Labroli Christine YangCharles Gill Jianying XiaoDavid Hesk Reynalda DeJesusJing Su Christopher M. TanPayal R. Sheth Michael KavanaDavid G. McLaren 《Analytical biochemistry》2017
The emergence of methicillin-resistant Staphylococcus aureus (MRSA) has created an urgent need for new therapeutic agents capable of combating this threat. We have previously reported on the discovery of novel inhibitors targeting enzymes involved in the biosynthesis of wall teichoic acid (WTA) and demonstrated that these agents can restore β-lactam efficacy against MRSA. In those previous reports pathway engagement of inhibitors was demonstrated by reduction in WTA levels measured by polyacrylamide gel electrophoresis. To enable a more rigorous analysis of these inhibitors we sought to develop a quantitative method for measuring whole-cell reductions in WTA. Herein we describe a robust methodology for hydrolyzing polymeric WTA to the monomeric component ribitol-N-acetylglucosamine coupled with measurement by LC-MS/MS. Critical elements of the protocol were found to include the time and temperature of hydrofluoric acid-mediated hydrolysis of polymeric WTA and optimization of these parameters is fully described. Most significantly, the assay enabled accurate and reproducible measurement of depletion EC50s for tunicamycin and representatives from the novel class of TarO inhibitors, the tarocins. The method described can readily be adapted to quantifying levels of WTA in tissue homogenates from a murine model of infection, highlighting the applicability for both in vitro and in vivo characterizations. 相似文献
103.
Submerged culture experiments were conducted in three phases to determine the optimal medium for rapidly producing conidia of the fungal bioherbicide Septoria polygonorum. In phase I, 47 crude carbon sources were evaluated to determine which would support sporulation. Under the conditions tested, pea brine (5–10% v/v) provided best conidiation. In phase II, a fractional factorial design was utilized to screen 38 different medium adjuncts in combination with pea brine for improved sporulation. MgSO4 was the only factor that resulted in a significant improvement. In phase III, a central composite design with response surface methodology was used to optimize concentrations of these critical factors. The model predicted optimal sporulation in a medium composed of 8.88% v/v pea brine+0.1 molar MgSO4 with an expected titer of 1.78×108 conidia/ml. Actual mean titer attained with the model-derived medium was 1.15×108 conidia/ml. No significant difference was observed in virulence of conidia produced on agar vs. the model-derived (liquid) medium. 相似文献
104.
The crystal structures of alkyl 2-deoxy-α-d-arabino-hexopyranosides, with the alkyl chain lengths from C8 to C18, are established by the single crystal X-ray structural determination. The even-alkyl chain length derivatives crystallized orthorhombic, with space group P212121, whereas the odd-alkyl chain length derivatives crystallized monoclinic, with space group P21. The sugar moieties retained a 4C1 chair conformation and the conformation of the alkyl chains was all-trans. The molecules formed a bilayer structure, in which alkyl chains were interdigitated. The hydrogen bonds, originating from the sugar moieties, were observed in adjacent layers and also within the same layer, resulting in the formation of infinite chains. The alkyl chains arranged parallel to each other and formed planar structures. The thermal properties of the alkyl 2-deoxy glucosides were analyzed further. It was observed that none of the derivatives exhibited mesomorphism. This study establishes that the absence of the hydroxyl group at C-2 of the sugar moiety results in a non-mesogenic nature of the alkyl 2-deoxy-α-d-glycosides, as opposed to the profound mesogenic nature of the normal alkyl glycosides. 相似文献
105.
A.M. Marqués A. Pinazo F.J. Aranda A. Ortiz M.J. Espuny 《Chemistry and physics of lipids》2009,158(2):110-726
This study analyzed the chemical and physical properties of a biosurfactant synthesized by Rhodococcus sp. 51T7. The biosurfactant was a trehalose tetraester (THL) consisting of six components: one major and five minor. The hydrophobic moieties ranged in size from 9 to 11 carbons. The critical micelle concentration (CMC) was 0.037 g L−1 and the interfacial tension against hexadecane was 5 mN m−1. At pH 7.4 the glycolipid CMC/critical aggregation concentration (CAC) was 0.05 g L−1 and at pH 4 it was 0.034 g L−1. A phase diagram revealed effective emulsification with water and paraffin or isopropyl myristate. A composition of 11.3-7.5-81.8 (isopropyl myristate-THL-W) was stable for at least 3 months. The HLB was 11 and the phase behaviour of the glycolipid revealed the formation of lamellar and hexagonal liquid-crystalline textures. 相似文献
106.
In vitro neural networks of cortical neurons interfaced to a computer via multichannel microelectrode arrays (MEA) provide a unique paradigm to create a hybrid neural computer. Unfortunately, only rudimentary information about these in vitro network's computational properties or the extent of their abilities are known. To study those properties, a liquid state machine (LSM) approach was employed in which the liquid (typically an artificial neural network) was replaced with a living cortical network and the input and readout functions were replaced by the MEA-computer interface. A key requirement of the LSM architecture is that inputs into the liquid state must result in separable outputs based on the liquid's response (separation property). In this paper, high and low frequency multi-site stimulation patterns were applied to the living cortical networks. Two template-based classifiers, one based on Euclidean distance and a second based on a cross-correlation were then applied to measure the separation of the input-output relationship. The result was over a 95% (99.8% when nonstationarity is compensated) input reconstruction accuracy for the high and low frequency patterns, confirming the existence of the separation property in these biological networks. 相似文献
107.
Field performance evaluation and genetic integrity assessment of cryopreserved papaya clones 总被引:1,自引:0,他引:1
This paper is the first report of field performance and evaluation of morphological traits following cryopreservation in four
genotypes of Carica papaya (Z6, 97, TS2 and 35). It also describes the successful establishment of in vitro plantlets following vitrification-based
cryopreservation of shoot tips and their acclimatisation through to field establishment. Cloned plants resulting from untreated
controls, as well as controls taken at three other stages of the cryopreservation process (dissection, pre-treatment, plant
vitrification solution 2 (PVS2) treatment) and cryopreserved plants were established to ensure a rigorous appraisal of any
variation. Results indicate no differences between any of the control plants or cryopreserved plants for either growth performance
or morphology. In addition, both randomly amplified DNA fingerprinting and amplified DNA methylation polymorphism markers
were used to assess any genomic or methylation changes in genotype 97 at four different developmental stages post cryopreservation
(in vitro, acclimatisation and field). Only small genomic DNA modifications (0–8.3%) were detected in field stage plants and
methylation modifications (0–4.3%) were detected at both the in vitro and field stages for samples treated with PVS2 or cryopreservation. 相似文献
108.
酿酒酵母菌核糖体RNA沉降系数的初步研究 总被引:1,自引:0,他引:1
为研究酿酒酵母菌核糖体RNA(rRNA)的沉降系数,用酶解法和液氮研磨法裂解酿酒酵母菌的细胞壁,Trizol Reagent提取其总RNA,同时提取小白鼠和斑马鱼的总RNA进行比较.经紫外分光光度计检测和甲醛琼脂糖变性胶电泳后,RNA纯度好,条带清晰,无弥散或降解现象.试验发现,与酶解法相比,用液氮研磨法破碎酿酒酵母菌细胞壁提取总RNA所用的成本低,时间少,产率和纯度高,适用于少量样品RNA的提取.同时,酿酒酵母菌与斑马鱼和小白鼠总RNA电泳图谱表明,三者的"18S rRNA"在条带大小方面差异较小,而"28S rRNA"差异较大.利用分析型离心机测得的酿酒酵母菌两个较大rRNA的沉降系数分别为24.7S和18.1S.研究结果表明了真核生物rRNA种类的多样性. 相似文献
109.
Colin I. Smith Benjamin T. Fuller Kyungcheol Choy Michael P. Richards 《Analytical biochemistry》2009,390(2):165-2988
We report a three-phase chromatographic method for the separation and analysis of δ13C values of underivatized amino acids from biological proteins (keratin, collagen, and casein) using liquid chromatography-isotope ratio mass spectrometry (LC-IRMS). Both precision and accuracy of δ13C values for standard amino acid mixtures over the range of approximately 8 to 1320 ng of carbon per amino acid on the column were assessed. The precision of δ13C values of amino acids was found to be better at higher concentrations, whereas accuracy improved at lower concentrations. The optimal performance for this method was achieved with between 80 and 660 ng of carbon of each amino acid on the column. At amino acid amounts lower than 20 ng of carbon on the column, precision and accuracy may become compromised. The application of this new three-phase chromatographic technique will allow the analysis of δ13C of amino acids to be carried out as a routine method and benefit fields of research such as biomedicine, forensics, ecology, nutrition, and palaeodiet reconstruction in archaeology. 相似文献
110.
Oxidation processes of lipids are of paramount interest from many viewpoints. For instance, oxidation processes are highly important under in vivo conditions because molecules with regulatory functions are generated by oxidation of lipids or free fatty acids. Additionally, many inflammatory diseases are accompanied by lipid oxidation and, therefore, oxidation products are also useful disease (bio)markers. Thus, there is also considerable interest in methods of (oxidized) lipid analysis.Nowadays, soft ionization mass spectrometric (MS) methods are regularly used to study oxidative lipid modifications due to their high sensitivities and the extreme mass resolution. Although electrospray ionization (ESI) MS is so far most popular, applications of matrix-assisted laser desorption and ionization (MALDI) MS are increasing. This review aims to summarize the so far available data on MALDI analyses of oxidized lipids. In addition to model systems, special attention will be paid to the monitoring of oxidized lipids under in vivo conditions, particularly the oxidation of (human) lipoproteins. It is not the aim of this review to praise MALDI as the “best” method but to provide a critical survey of the advantages and drawbacks of this method. 相似文献