Search results for "HYDROXYLAMINE"
showing 10 items of 34 documents
A concise route to MK-4482 (EIDD-2801) from cytidine.
2020
A two-step route to MK-4482 (EIDD-2801, 1) was developed consisting of an esterification and hydroxamination of cytidine. The selective acylation and direct amination eliminate the need for protecting and activating groups and proceed in overall yield of 75%, a significant advancement over the reported yield of 17%. The step count is reduced from five transformations to two, and expensive uridine is replaced with the more available cytidine.
Hydroxylamine released by nitrifying microorganisms is a precursor for HONO emission from drying soils
2018
AbstractNitrous acid (HONO) is an important precursor of the hydroxyl radical (OH), the atmosphere´s primary oxidant. An unknown strong daytime source of HONO is required to explain measurements in ambient air. Emissions from soils are one of the potential sources. Ammonia-oxidizing bacteria (AOB) have been identified as possible producers of these HONO soil emissions. However, the mechanisms for production and release of HONO in soils are not fully understood. In this study, we used a dynamic soil-chamber system to provide direct evidence that gaseous emissions from nitrifying pure cultures contain hydroxylamine (NH2OH), which is subsequently converted to HONO in a heterogeneous reaction w…
Phosphorylated intermediate of a transport ATPase and activity of protein kinase in membranes from corn roots
1983
A maize-root microsomal fraction was enriched in ATPase by treatment with Triton X-100. This activity, which reached 1.2-2.0/mumol Pi x min-1 x mg protein-1, was specific for ATP, very slightly stimulated by K+, inhibited by orthovanadate and diethylstilbestrol, resistant to oligomycin and azide, and had a Km of 1.2 mM MgATP. Incubation of the microsomal fraction with [gamma 32-P]ATP followed by electrophoresis in acid conditions revealed the presence of several phosphoproteins. The phosphorylation of a 110000-Mr polypeptide reached the steady-state level in less than 5 s and rapidly turned over the phosphate group. The phosphorylation level was an hyperbolic function of the [ATP] with a Km…
The Tonoplast H+ -ATPase of Acer pseudoplatanus is a vacuolar-type ATPase that operates with a phosphoenzyme intermediate
1995
The tonoplast H+-ATPase of Acer pseudoplatanus has been purified from isolated vacuoles. After solubilization, the purification procedure included size-exclusion and ion-exchange chromatography. The H+-ATPase consists of at least eight subunits, of 95, 66, 56, 54, 40, 38, 31, and 16 kD, that did not cross-react with polyclonal antibodies raised to the plasmalemma ATPase of Arabidopsis thaliana. The 66-kD polypeptide cross-reacted with monoclonal antibodies raised to the 70-kD subunit of the vacuolar H+-ATPase of oat roots. The functional molecular size of the tonoplast H+-ATPase, analyzed in situ by radiation inactivation, was found to be around 400 kD. The 66-kD subunit of the tonoplast H+…
Die kationische ɛ-caprolactam-polymerisation. IV. Isolierung und strukturermittlung der oligomeren als beitrag zur aufklärung des polymerisationsmech…
1966
Molekulareinheitliche Oligomere von Polykondensations- und Polyadditionsreaktionen konnen zur Aufklarung von Struktur und Bildungsmechanismus der Polymeren dienen. Auf diesem Wege wird der fruher vorgeschlagene Mechanismus der kationischen Lactampolymerisation mit wasserfreien Sauren erhartet, der in einer Acylierung des Lactams durch Lactamsalz unter Bildung von Aminoacyllactamsalz und nachfolgendem Kettenwachstum durch Addition weiterer Lactammolekule an die entstandene und immer wieder neu gebildete Ammonium-Endgruppe besteht. Dazu werden aus Caprolactam und Chlorwasserstoff als Initiator unter geeigneten Bedingungen Oligomerengemische gewonnen und elektrophoretisch aufgetrennt. Mikropra…
Quantitative evaluation of oxidative stress status on peripheral blood in beta-thalassaemic patients by means of electron paramagnetic resonance spec…
2005
Summary High oxidative stress status (OSS) is known to be one of the most important factors determining cell injury and consequent organ damage in thalassaemic patients with secondary iron overload. Using an innovative hydroxylamine ‘radical probe’ capable of efficiently trapping majority of oxygen-radicals including superoxide we measured, by electron paramagnetic resonance (EPR) spectroscopy, OSS in peripheral blood of 38 thalassaemic patients compared with sex-/age-matched healthy controls. Thalassaemic patients showed sixfold higher EPR values of OSS than controls. Significantly higher EPR values of OSS were observed in those with a severe phenotype (thalassaemia major, transfusion-depe…
Synthesis of [1,2]oxazolo[5,4-e]indazoles as antitumour agents
2013
Abstract A series of 40 derivatives of the [1,2]oxazolo[5,4-e]indazoles ring system have been prepared with good yields using a versatile and convenient route. Annelation of the [1,2]oxazole ring on the indazole-4-one system was achieved by reaction of the corresponding enaminoketones with hydroxylamine hydrochloride. Derivatives of the title ring system were tested by the National Cancer Institute of Bethesda and one of them (13t) showed growth-inhibitor activity against all the 54 human tumour cell lines generally at low micromolar concentrations.
Synthesis, crystal structure and magnetic properties of a new [ZnII6DyIII6] dodecanuclear motif
2013
Abstract A new dodecanuclear complex, [{(HL)(L)(dmf)ZnIIDyIII(dmf)(H2O)}6]·3dmf·4.2H2O has been assembled using a supramolecular compartmental ligand (H3L results from the condensation reaction of 3-formylsalicylic acid and hydroxylamine). The six DyIII ions describe an octahedron that is inscribed into the octahedron generated by the zinc(II) ions each DyIII ion from this motif behaving as a single ion magnet.
Determination of kinetic parameters of redox reactions using CE‐ICP‐MS: A case study for the reduction of Np(V) by hydroxylamine hydrochloride
2018
The rate constants k of the reduction of 5 × 10-5 M Np(V) to Np(IV) by hydroxylamine hydrochloride (HAHCl) in 1 M HCl have been determined by CE-ICP-MS in the temperature range of ϑ = 30-70°C and with varying concentrations of HAHCl from 1 to 7.2 M. The reaction was found to have (pseudo)first order kinetics with respect to HAHCl. The experimental results for k ranged from 0.0029(1) min-1 (ϑ = 40°C, c(HAHCl) = 3 M) to 0.039(7) min-1 (ϑ = 60°C, c(HAHCl) = 7.2 M). The activation energy of the reaction was determined as EA = (72 ± 10) kJ/mol. These results and a comparison with literature data show that the coupling of CE to ICP-MS provides a powerful analytical tool for the investigation of…
Fluorinated Heterocyclic Compounds− The First Example of an Irreversible Ring-Degenerate Rearrangement on Five-Membered Heterocycles by Attack of an …
2004
The reactions of 5-perfluoroalkyl-1,2,4-oxadiazoles 3 with hydroxylamine in DMF give the regioisomeric 3-perfluoroalkyl-1,2,4-oxadiazoles 4 in excellent yields. This process is the first example of ring-degenerate rearrangement (RDR) occurring on five-membered heterocycles by attack of an external bidentate nucleophile, which replaces two heteroatoms of the ring. We suggest that an ANRORC-like mechanism occurs in which the addition of the nucleophilic nitrogen atom (NH2OH) on the C(5) atom of 3 is followed by ring opening and irreversible ring-degenerate closure by attack of the nucleophilic oxygen atom (=NOH) on the C(3) atom of the original ring, realizing an elegant and efficient synthes…