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Engelhardt, Annika ; Ebeling, Marco ; Kaltenegger, Elisabeth , et al. Anal. Bioanal. Chem.,2024. DOI: 10.1007/s00216-024-05613-1 PubMed ID: 39443363
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Abstract: Acetohydroxyacid synthase (AHAS, EC 2.2.1.6) catalyzes the frst step in the synthesis of the branched-chain amino acids valine, leucine, and isoleucine, pathways being present in plants and microorganisms, but not in animals. Thus, AHAS is an important target for numerous herbicides and, more recently, for the development of antimicrobial agents. The need to develop new and optimized herbicides and pharmaceuticals requires a detailed understanding of the biochemistry of AHAS. AHAS transfers an activated two-carbon moiety derived from pyruvate to either pyruvate or 2-oxobutyrate as acceptor substrates, forming 2-acetolactate or 2-acetohydroxy-2-butyrate, respectively. Various methods have been described in the literature to biochemically characterize AHAS with respect to substrate preferences, substrate specifcity, or kinetic parameters. However, the simultaneous detection and quantifcation of substrates and unstable products of the AHAS-catalyzed reaction have always been a challenge. Using AHAS isoform II from Escherichia coli, we have developed a sensitive assay for AHAS-catalyzed reactions that uses derivatization with ethyl chloroformate to stabilize and volatilize all reactants in the aqueous solution and detect them by gas chromatography coupled to fame ionization detection or mass spectrometry. This assay allows us to characterize the product formation in reactions in single and dual substrate reactions and the substrate specifcity of AHAS, and to reinterpret previous biochemical observations. This assay is not limited to the AHAS-catalyzed reactions, but should be applicable to studies of many metabolic pathways.
Keywords: Acetolactate synthase ; Branched-chain amino acid biosynthesis ; Derivatization ; Ethyl chloroformate ; Kinetics ; Substrate specifcity
Purchased from AmBeed: 15933-07-0
CAS No. : | 15933-07-0 | MDL No. : | MFCD03265336 |
Formula : | C6H10O3 | Boiling Point : | - |
Linear Structure Formula : | - | InChI Key : | FJAKCEHATXBFJT-UHFFFAOYSA-N |
M.W : | 130.14 | Pubchem ID : | 85195 |
Synonyms : |
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Signal Word: | Warning | Class: | N/A |
Precautionary Statements: | P261-P280-P305+P351+P338 | UN#: | N/A |
Hazard Statements: | H302-H315-H319-H332-H335 | Packing Group: | N/A |
GHS Pictogram: |
* All experimental methods are cited from the reference, please refer to the original source for details. We do not guarantee the accuracy of the content in the reference.
Yield | Reaction Conditions | Operation in experiment |
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98% | With iodine; In dimethyl sulfoxide; at 80℃; for 0.00833333h;Green chemistry; | General procedure: A mixture of methylcarbonyl (1 mmol), thiourea (1.5 mmol), I2(1 mmol) and Nizeolite-Im-IL (15 mg) in DMSO (2 mL) was stirred at 80 C for desired time. Afterthe satisfactory completion of the reaction (monitored by TLC), the nanocatalystwas separated through centrifugation. The reaction media (DMSO) was quenchedby adding ammonia to pH = 9-10 to give the solid products. Finally, the pure productwas recrystallized from ethanol at a high yield. All 2-aminothiazole products areknown and were identified by comparing their melting point, FT-IR and 1H NMRwith authentic samples. |