Phenol metabolism hydroxylase

Mathematical models of benzene and phenol metabolism suggest that the inhibition by benzene of phenol metabolism, and by phenol on benzene metabolism, occurs through competition for a common reaction site, which can also bind catechol and hydroquinone (Schlosser et al. 1993). Flavonoids have been shown to inhibit phenol hydroxylase or increase phenol hydroxylase activity in a dose-dependent manner, dependent on the oxidation potential of the flavonoid (Hendrickson et al. 1994). 

The metabolism of fluorophenols by phenol hydroxylase from Trichosporium cutaneum, catechol 1,2-dioxygenase from Pseudomonas arvilla strain C-1, and by the fungus Exophilia jeanselmei has been examined, and detailed NMR data were given for the ring fission flnoromnconates (Boersma et al. 1998). 

The metabolism of a range of fluorophenols containing up to five fluorine substituents was examined using phenol hydroxylase from Trichosporon cutaneum (Peelen et al. 1995). Fluorocatechols were formed, with loss of fluoride for some substrates. 

Because LCEC had its initial impact in neurochemical analysis, it is not, surprising that many of the early enzyme-linked electrochemical methods are of neurologically important enzymes. Many of the enzymes involved in catecholamine metabolism have been determined by electrochemical means. Phenylalanine hydroxylase activity has been determined by el trochemicaUy monitoring the conversion of tetrahydro-biopterin to dihydrobiopterin Another monooxygenase, tyrosine hydroxylase, has been determined by detecting the DOPA produced by the enzymatic reaction Formation of DOPA has also been monitored electrochemically to determine the activity of L-aromatic amino acid decarboxylase Other enzymes involved in catecholamine metabolism which have been determined electrochemically include dopamine-p-hydroxylase phenylethanolamine-N-methyltransferase and catechol-O-methyltransferase . Electrochemical detection of DOPA has also been used to determine the activity of y-glutamyltranspeptidase The cytochrome P-450 enzyme system has been studied by observing the conversion of benzene to phenol and subsequently to hydroquinone and catechol... 

The amino acid phenylalanine is derived from gallic acid, being this compound biosynthesized in the shikimic acid metabolic route. Most of the phenolic compounds from higher plants are also derived from this amino acid, formed in the phenylpropanoid metabolic route, in the cell cytoplasm, being various enzymes involved in this metabolism. Phenylalanine ammonia lyase interacts with phenylalanine forming cinnamic acid, that is, hydrolyzed by citmamate-4-hydroxylase, rendering p-coumaric acid. Different hydroxylations and/or methoxylations, of this... 

An important group of mixed function oxidases which occur in all types of organism and which are critical in the metabolism of the aromatic amino adds and other aromatic substrates are the aromatic hydroxylases. Their mode of action, the overall stoichiometry of which is represented in the sequence below, results in the introduction of a phenolic hydroxyl group in an aromatic ring system and has been the subject of intensive study. Pyridine and flavin nucleotides, cytochromes, metals (Fe, Cu), ascorbate and pteridine derivatives (H2X) may serve as electron donors. Most, but not all, of these en2yme reactions require transition metal ions for full activity. 

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