67896-55-3

Upstream product

• 51-41-2 norepinephrine 

Downstream Products

• 115331-10-7 5-S-Cysteinylepinephrine 

Relevant academic research and scientific papers

METAL-ORGANIC FRAMEWORKS FOR ELECTROCHEMICAL DETECTION OF ANALYTES

In some embodiments, the present disclosure pertains to methods of detecting an analyte in a sample by associating the sample with an electrode that includes a metal-organic framework. After association, the redox properties of the electrode are evaluated. Thereafter, the presence or absence of the analyte in the sample is detected by correlating the redox properties of the electrode to the presence or absence of the analyte. In some embodiments, the present disclosure pertains to electrodes that include a metal-organic framework and an electrode surface. In particular embodiments of the present disclosure, the metal-organic framework is associated with the electrode surface. Additional embodiments of the present disclosure pertain to methods of making the electrodes of the present disclosure by associating a metal-organic framework with an electrode surface. In some embodiments, the methods of the present disclosure also include a step of mixing the metal-organic framework with a polymer.

A New Quantification Method Using Electrochemical Mass Spectrometry

Mass spectrometry-based quantification method has advanced rapidly. In general, the methods for accurate quantification rely on the use of authentic target compounds or isotope-labeled compounds as standards, which might be not available or difficult to synthesize. To tackle this grand challenge, this paper presents a novel approach, based on electrochemistry (EC) combined with mass spectrometry (MS). In this approach, a target compound is allowed to undergo electrochemical oxidation and then subject to MS analysis. The oxidation current recorded from electrochemistry (EC) measurement provides information about the amount of the oxidized analyte, based on the Faraday’s Law. On the other hand, the oxidation reaction yield can be determined from the analyte MS signal changes upon electrolysis. Therefore, the total amount of analyte can be determined. In combination with liquid chromatography (LC), the method can be applicable to mixture analysis. The striking strength of such a method for quantitation is that neither standard compound nor calibration curve is required. Various analyte molecules such as dopamine, norepinephrine, and rutin as well as peptide glutathione in low quantity were successfully quantified using our method with the quantification error ranging from ? 2.6 to +?4.6%. Analyte in a complicated matrix (e.g., uric acid in urine) was also accurately measured. [Figure not available: see fulltext.].

Stereospecificity of mushroom tyrosinase immobilized on a chiral and a nonchiral support

Mushroom tyrosinase was immobilized from an extract onto glass beads covered with the cross-linked totally cinnamoylated derivates of D-sorbitol (sorbitol cinnamate) and glycerine (glycerine cinnamate). The enzyme was immobilized onto the support by direct adsorption, and the quantity of immobilized tyrosinase was higher for sorbitol cinnamate, the support with the higher number of esterified hydroxyls per unit of monosacharide, than for glycerine cinnamate. The results obtained from the stereospecificity study of the monophenolase and diphenolase activity of immobilized mushroom tyrosinase are reported. The enantiomers L-tyrosine, DL-tyrosine, D-tyrosine, L-dopa, DL-dopa, D-dopa, L-α-methyldopa, DL-α-methyldopa, L-isoprenaline, DL-isoprenaline, L-adrenaline, DL-adrenaline, L-noradrenaline, and D-noradrenaline were assayed with tyrosinase immobilized on a chiral support (sorbitol cinnamate), whereas L-tyrosine, DL-tyrosine, D-tyrosine, L-dopa, DL-dopa, D-dopa, L-α-methyldopa, and DL-α-methyldopa were assayed with tyrosinase immobilized on a nonchiral support (glycerine cinnamate). The same Vmaxapp values for each series of enantiomers were obtained. However, the Kmapp values were different, the L isomers showing lower values than the DL isomers, whereas the highest K mapp value was obtained with D isomers. No difference was observed in the stereospecificity of tyrosinase immobilized on a chiral (sorbitol cinnamate) or nonchiral (glycerine cinnamate) support.

Metallo-ROS in Alzheimer's disease: Oxidation of neurotransmitters by CuII-β-amyloid and neuropathology of the disease

A clear mind: The CuII-β-amyloid (Aβ) complex has been shown to exhibit enzyme-like metal-centered oxidative and hydroxylation catalyses. Metal-centered oxidation of various neurotransmitters by CuAβ under biomimetic conditions has verified the bio-relevance of the metal-centered catalyses and is expected to provide a chemical basis for the better understanding of the etiology of Alzheimer's disease. ROS = reactive oxygen species. (Figure Presented).

Oxidative metabolites of 5-S-cysteinylnorepinephrine are irreversible inhibitors of mitochondrial complex I and the α-ketoglutarate dehydrogenase and pyruvate dehydrogenase complexes: Possible implications for neurodegenerative brain disorders

The major initial product of the oxidation of norepinephrine (NE) in the presence of L-cysteine is 5-S-cysteinylnorepinephrine which is then further easily oxidized to the dihydrobenzothiazine (DHBT) 7-(1-hydroxy-2-aminoethyl)-3,4-dihydro-5-hydroxy-2H-1,4-benzothia zine-3-carboxylic acid (DHBT-NE-1). When incubated with intact rat brain mitochondria, DHBT-NE-1 evokes rapid inhibition of complex I respiration without affecting complex II respiration. DHBT-NE-1 also evokes time- and concentration-dependent irreversible inhibition of NADH-coenzyme Q1 (CoQ1) reductase, the pyruvate dehydrogenase complex (PDHC), and α-ketoglutarate dehydrogenase (α-KGDH) when incubated with frozen and thawed rat brain mitochondria (mitochondrial membranes). The time dependence of the inhibition of NADH-CoQ1 reductase, PDHC, and α-KGDH by DHBT-NE-1 appears to be related to its oxidation, catalyzed by an unknown component of the inner mitochondrial membrane, to electrophilic intermediates which bind covalently to active site cysteinyl residues of these enzyme complexes. The latter conclusion is based on the ability of glutathione to block inhibition of NADH-CoQ1 reductase, PDHC, and α-KGDH by scavenging electrophilic intermediates, generated by the mitochondrial membrane-catalyzed oxidation of DHBT-NE-1, forming glutathionyl conjugates, several of which have been isolated and spectroscopically identified. The possible implications of these results to the degeneration of neuromelanin-pigmented noradrenergic neurons in the locus ceruleus in Parkinson's disease are discussed.