scholarly journals HPLC purification technique: synthesis of unsymmetrical thiobarbituric acids

Heliyon ◽  
2019 ◽  
Vol 5 (7) ◽  
pp. e02008
Author(s):  
Vinod D. Deotale ◽  
Manish M. Katiya ◽  
Madhukar G. Dhonde
2019 ◽  
Author(s):  
Seth Herzon ◽  
Alan R. Healy ◽  
kevin wernke ◽  
Chung Sub Kim ◽  
Nicholas Lees ◽  
...  

<div>The clb gene cluster encodes the biosynthesis of metabolites known as precolibactins and colibactins. The clb pathway is found in gut commensal E. coli, and clb metabolites are thought to initiate colorectal cancer via DNA cross-linking. Precolibactin 886 (1) is one of the most complex isolated clb metabolites; it contains a 15-atom macrocycle and an unusual 5-hydroxy-3-oxazoline ring. Here we report confirmation of the structural assignment via a biomimetic synthesis of precolibactin 886 (1) proceeding through the amino alcohol 9. Double oxidation of 9 afforded the unstable α-ketoimine 2 which underwent macrocyclization to precolibactin 886 (1) upon HPLC purification (3% from 9). Studies of the putative precolibactin 886 (1) biosynthetic precursor 2, the model α-ketoimine 25, and the α-dicarbonyl 26 revealed that these compounds are susceptible to nucleophilic rupture of the C36–C37 bond. Moreover, cleavage of 2 produces other known clb metabolites or biosynthetic intermediates. This unexpected reactivity explains the difficulties in isolating full clb metabolites and accounts for the structure of a recently identified colibactin–adenine adduct. The colibactin peptidase ClbP deacylates synthetic precolibactin 886 (1) to form a non-genotoxic pyridone, suggesting precolibactin 886 (1) lies off-path of the major biosynthetic route.</div>


PLoS ONE ◽  
2019 ◽  
Vol 14 (6) ◽  
pp. e0217883
Author(s):  
Jan Lennart von Hacht ◽  
Sarah Erdmann ◽  
Lars Niederstadt ◽  
Sonal Prasad ◽  
Asja Wagener ◽  
...  

2013 ◽  
Vol 69 (10) ◽  
pp. 2072-2080 ◽  
Author(s):  
Adam Round ◽  
Elizabeth Brown ◽  
Romain Marcellin ◽  
Ulrike Kapp ◽  
Corey S. Westfall ◽  
...  

The combination of protein crystallography and small-angle X-ray scattering (SAXS) provides a powerful method to investigate changes in protein conformation. These complementary structural techniques were used to probe the solution structure of the apo and the ligand-bound forms of theArabidopsis thalianaacyl acid–amido synthetase GH3.12. This enzyme is part of the extensive GH3 family and plays a critical role in the regulation of plant hormones through the formation of amino-acid-conjugated hormone productsviaan ATP-dependent reaction mechanism. The enzyme adopts two distinct C-terminal domain orientations with `open' and `closed' active sites. Previous studies suggested that ATP only binds in the open orientation. Here, the X-ray crystal structure of GH3.12 is presented in the closed conformation in complex with the nonhydrolysable ATP analogue AMPCPP and the substrate salicylate. Using on-line HPLC purification combined with SAXS measurements, the most likely apo and ATP-bound protein conformations in solution were determined. These studies demonstrate that the C-terminal domain is flexible in the apo form and favours the closed conformation upon ATP binding. In addition, these data illustrate the efficacy of on-line HPLC purification integrated into the SAXS sample-handling environment to reliably monitor small changes in protein conformation through the collection of aggregate-free and highly redundant data.


2010 ◽  
Vol 82 (1) ◽  
pp. 39-55 ◽  
Author(s):  
Rajasekar R. Prasanna ◽  
Mookambeswaran A. Vijayalakshmi

Immobilized metal-ion affinity (IMA) adsorption is a collective term that is used to include all kinds of adsorptions where the metal ion serves as the characteristic and most essential part of adsorption center. Of all the IMA techniques, immobilized metal-affinity chromatography (IMAC) has been gaining popularity as the choice of purification technique for proteins. IMAC represents a separation technique that is primarily useful for proteins with natural surface exposed-histidine residues and for recombinant proteins with engineered histidine tag. This review also gives insight into other nonchromatographic applications of IMA adsorption such as immobilized metal-ion affinity gel electrophoresis (IMAGE), immobilized metal-ion affinity capillary electrophoresis (IMACE), and immobilized metal-ion affinity partitioning (IMAP).


Author(s):  
A. M. Vandenbroucke ◽  
R. Morent ◽  
N. De Geyter ◽  
C. Leys

AbstractThe aim of this paper is to give a review of the research on the decomposition of trichloroethylene (TCE), a common industrial solvent, with combined use of non-thermal plasma and heterogeneous catalysis, i.e. plasma-catalysis. This air purification technique has been investigated over the last decade in an effort to overcome the disadvantages of non-thermal plasma treatment of waste air containing volatile organic compounds (VOCs). Some examples of different plasma technologies used for plasma-catalysis are given. These include the dielectric barrier discharge, the pulsed corona discharge and the atmospheric pressure glow discharge. In a plasma-catalytic hybrid system the catalyst can either be located in the discharge region or downstream of the plasma reactor. The mechanisms that drive both configurations are briefly discussed, followed by an extended literature overview of the removal of TCE with plasma-catalysis.


Synthesizer suggests the chief feature element of clocking around modern-day high-speed energy systems. Every time appreciated seeing that for a phase-locked land (PLL), numbers synthesizers illustrate fantastic precision and even now let general object rendering linked with programmable numbers switching. While doing this dissertation lots of people deliver a certainly better model linked with Steadiness synthesizer coupled with focused on ugly Steadiness synthesizers implementing An electronic digital PLL. A persons vision might be globally placing and also specifications because of the straightforward varieties in the An electronic digital PLL: phase-frequency system, bill tubing, land purification technique, present-day dictated oscillator (VCO) coupled with programmable divider. This particular emulator achievement in the An electronic digital PLL implementing perhaps the most common 0.18µd CMOS technology around Piquance illustrate a fast wrapping up effort frame tremendous numbers range. This particular acquire length of time could be tailored via altering ones own bill tubing latest also,the land purification technique capacitor. PFD (Phase Steadiness Detector) marketplace forestalling deviation in the bill tubing marketplace under the founded problem might be designed. That comprehension of the LPF needs the published research within the land individual in the PLL. Encapsulating the perfect tradeoffs for illustration acquire alter, acquire an important portions of knowledge switch cost, this will likely often be simply just ones own tricky obstruct so that you can design. To acquire wider production numbers concentrating on alter, bigger capacitance is vital (i.e., great area). Which will boost the occasionally keeps going free of boost laptop computer food put usage, The project acknowledges some form of voltage-controlled oscillator (VCO) implementing a diamond ring diamond ring linked with single-ended current-starved oscillator can present tremendous jogging frequencies.


2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Suqin Gao ◽  
Yun Kong ◽  
Jing Yu ◽  
Lihong Miao ◽  
Lipeng Ji ◽  
...  

Abstract Background Harmful cyanobacterial blooms have attracted wide attention all over the world as they cause water quality deterioration and ecosystem health issues. Microcystis aeruginosa associated with a large number of bacteria is one of the most common and widespread bloom-forming cyanobacteria that secret toxins. These associated bacteria are considered to benefit from organic substrates released by the cyanobacterium. In order to avoid the influence of associated heterotrophic bacteria on the target cyanobacteria for physiological and molecular studies, it is urgent to obtain an axenic M. aeruginosa culture and further investigate the specific interaction between the heterotroph and the cyanobacterium. Results A traditional and reliable method based on solid-liquid alternate cultivation was carried out to purify the xenic cyanobacterium M. aeruginosa FACHB-905. On the basis of 16S rDNA gene sequences, two associated bacteria named strain B905–1 and strain B905–2, were identified as Pannonibacter sp. and Chryseobacterium sp. with a 99 and 97% similarity value, respectively. The axenic M. aeruginosa FACHB-905A (Microcystis 905A) was not able to form colonies on BG11 agar medium without the addition of strain B905–1, while it grew well in BG11 liquid medium. Although the presence of B905–1 was not indispensable for the growth of Microcystis 905A, B905–1 had a positive effect on promoting the growth of Microcystis 905A. Conclusions The associated bacteria were eliminated by solid-liquid alternate cultivation method and the axenic Microcystis 905A was successfully purified. The associated bacterium B905–1 has the potentiality to promote the growth of Microcystis 905A. Moreover, the purification technique for cyanobacteria described in this study is potentially applicable to a wider range of unicellular cyanobacteria.


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