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Chemical Cleavage of Peptide Bonds
Published in Roger L. Lundblad, Chemical Reagents for Protein Modification, 2020
The cleavage of protein at asparaginyl-glycyl peptide bonds with hydroxylamine36 has proved useful in selected circumstances. The reaction is generally performed in the presence of 6 M guanidium chloride at pH 9.0 with 2 M NH2OH. The pH of the solution is maintained either with a pH-stat or with 0.2 M potassium carbonate. Generally, as with other means of peptide bond cleavage, optimal results are obtained with the reduced and alkylated protein. The reaction will yield a new amino-terminal amino acid and aspartyl hydroxyamate.
Procedures for Writing Formulas and Naming Compounds
Published in Patrick E. McMahon, Rosemary F. McMahon, Bohdan B. Khomtchouk, Survival Guide to General Chemistry, 2019
Patrick E. McMahon, Rosemary F. McMahon, Bohdan B. Khomtchouk
Example: Name K2CO3Potassium: Direct (unchanged) name of the metal that forms the positive ion.Potassium is in Group I and is a fixed-charged metal; no Roman numeral is required.The name carbonate matches the formula (CO3) as the negative ion (charges are not shown); the name is used directly with no change and is stated last in the complete name of the compound. Name: potassium carbonate
Zearalenone: Insights into New Mechanisms in Human Health
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
Cornelia Braicu, Alina Andreea Zimta, Ioana Berindan-Neagoe
The most large-scale available procedure by which ZEA food concentration can be lowered is through processing. Boiling had a reduced effect on ZEA decontamination, but ZEA molecular structure can be destructed through oxidation, by exposure to ozone, H2O2, or heated alkaline water [5,13]. ZEN was almost completely degraded after only 5 seconds of exposure to 5 mg/L of ozone, and the ZEA- containing corn was decontaminated after 180 minutes at 100 mg/L O3 [93]. Adding sodium bicarbonate in the case of biscuits or potassium carbonate in the case of instant noodles can significantly decrease ZEA content. Wheat decortication as it is done in the process of obtaining white bread has a profound effect in reducing ZEA content [5].
Different chemical proteomic approaches to identify the targets of lapatinib
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2023
Tatjana Kovačević, Krunoslav Nujić, Mario Cindrić, Snježana Dragojević, Adrijana Vinter, Amela Hozić, Milan Mesić
A solution of N-[3-chloro-4-[(3-fluorophenyl)methoxy]phenyl]-6-[5-[(2-methylsulfonylethylamino)methyl]-2-furyl]quinazolin-4-amine (1) (70 mg, 0.120 mmol) and sodium hydride, 60% disperse in mineral oil (9.6 mg, 0.240 mmol) in DMF (2 ml) was cooled to 0 °C. 2-[2-(bromomethyl)-5-[3-(trifluoromethyl)diazirin-3-yl]phenyl]ethynyl-trimethyl-silane (45 mg, 0.120 mmol) was then added (Scheme 5). The solution was allowed to stir at room temperature overnight. 2 ml of MeOH and potassium carbonate (49.7 mg, 0.360 mmol) were added. The solution was stirred at room temperature for seven hours. The reaction mixture was quenched with 10 ml of water and extracted with EtOAc (3 × 30 ml). The solvent was evaporated under reduced pressure. The sample was purified by flush chromatography using a BIOTAGE SP1 purification device and a 10 g normal phase silica SNAP column (DCM-EtOH solvent system with a gradient rising from 0–10% of EtOH in 15 CV). After evaporation of the solvent, 15 mg of N-[3-chloro-4-[(3-fluorophenyl)methoxy]phenyl]-6-[5-[[[2-ethynyl-4-[3-(trifluoromethyl)diazirin-3-yl]phenyl]methyl-(2-methylsulfonylethyl)amino]methyl]-2-furyl]quinazolin-4-amine (4) was isolated as a yellow solid (yield = 14.5%).
Potential anti-neuroinflammatory NF-кB inhibitors based on 3,4-dihydronaphthalen-1(2H)-one derivatives
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2020
Yue Sun, Yan-Qiu Zhou, Yin-Kai Liu, Hong-Qin Zhang, Gui-Ge Hou, Qing-Guo Meng, Yun Hou
p-Hydroxybenzaldehyde (1.22 g, 0.1 mmol) and 3-fluorobenzylbromide (1.89 g, 0.1 mmol), 4-fluorobenzylbromide (1.89 g, 0.1 mmol), or 4-trifluoromethylbenzylbromide (2.39 g, 0.1 mmol) were dissolved in 50 ml of acetone. After anhydrous potassium carbonate (1.38 g, 0.3 mmol) was added, the mixtures were stirred at 60 °C for 2 h (monitored by TLC) and filtered to obtain filtrate. After removal of solvents under a vacuum, the residues were purified on a silica gel by column chromatography using petroleum ether/EtOAc (4:1, v/v) as the eluent to generate the intermediates: 4-((3-fluorobenzyl)oxy)benzaldehyde (8a), 4-((4-fluorobenzyl)oxy)benzaldehyde (8 b), and 4-((4-trifluoromethylbenzyl)oxy)benzaldehyde (8c). Compounds 5 (0.35 g, 2.0 mmol) and 8a (0.46 g, 2.0 mmol), 8 b (0.46 g, 2.0 mmol) or 8c (0.56 g, 2.0 mmol) were dissolved in 15 ml of methanol. After 6.0 ml of NaOH solution at 20% were added, the mixtures were stirred for 4–5 h at ambient temperature (monitored by TLC). The solvents were removed by pouring, and the residues were purified on a silica gel by column chromatography using petroleum ether/EtOAc (4:1, v/v) as the eluent to produce light yellow powders 7a-c.
Novel Quinoxaline-2-Carbonitrile-1,4-Dioxide Derivatives Suppress HIF1α Activity and Circumvent MDR in Cancer Cells
Published in Cancer Investigation, 2018
Alexander M. Scherbakov, Alexander M. Borunov, Galina I. Buravchenko, Olga E. Andreeva, Igor A. Kudryavtsev, Lyubov G. Dezhenkova, Andrey E. Shchekotikhin
The series of 3-aryl/hetaryl-quinoxaline-2-carbo-nitrile-1,4-dioxides 2a-m was synthesized by the Beirut reaction (Figure 2). Target compounds were obtained by condensation of corresponding benzofuroxanes 3a-g and acylacetonitriles 4a-g in the presence of a base (Table 1). These starting mono- or disubstituted benzofuroxanes 3a-g and acylacetonitriles 4a-g were obtained by previously described methods (20,27). Two reaction conditions for the Beirut reaction were examined. First, substoichiometric quantities of potassium carbonate as a base in ethanol at room temperature (Method A) was tested (23). In cases of fluoro derivatives (2c, f, h-m), low yield (15% to 45%) of target products was observed. The second condition tested was substoichiometric quantities of triethylamine as the base in chloroform at room temperature (Method B) (36). This generates notably higher yields of target compounds than method A (Table 1). The structure of final quinoxaline-2-carbonitrile-1,4-dioxides 2a-m was elucidated by NMR and HRMS spectra and their purity (>95%) by HPLC.