Indole oxidase

Kampa, L. and Peisach, J. (1980) Purification and characterization of hydroxy indole oxidase from the gills of Mytilus edulis. J. Biol. Chem., 255, 595-601. 

In addition to activities ordinarily ascribed to them, peroxidase and catalase possess properties as oxygen transferases and mixed function oxidases. They may exist in functionally active ferrous forms which have, like hemc lobin and myoglobin, the property of combining with molecular oxygen. This oxygen may be transferred to substrate, or be reduced in steps. For purposes of the present review, mechanisms that have been proposed for peroxidatic and catalatic oxidations will be summarized and followed by discussion of dihydroxyfumaric acid oxidase, tryptophan oxidase, and indolyl-acetic oxidase and related oxidases, and indole oxidase. All of these have properties in common with peroxidase and catalase. 

The synthesis and metabolism of trace amines and monoamine neurotransmitters largely overlap [1]. The trace amines PEA, TYR and TRP are synthesized in neurons by decarboxylation of precursor amino acids through the enzyme aromatic amino acid decarboxylase (AADC). OCT is derived from TYR. by involvement of the enzyme dopamine (3-hydroxylase (Fig. 1 DBH). The catabolism of trace amines occurs in both glia and neurons and is predominantly mediated by monoamine oxidases (MAO-A and -B). While TYR., TRP and OCT show approximately equal affinities toward MAO-A and MAO-B, PEA serves as preferred substrate for MAO-B. The metabolites phenylacetic acid (PEA), hydroxyphenylacetic acid (TYR.), hydroxymandelic acid (OCT), and indole-3-acetic (TRP) are believed to be pharmacologically inactive. 

LUDWIG-MULLER, J., HILGENBERG, W., A plasma membrane-bound enzyme oxidases L-tryptophan to indole-3-acetaldoxime, Physiol. Plant., 1988, 74, 240-250. 

Compounds I and II are quite stable at low temf>erature and therefore can serve as pure reactants to study the mechanisms of peroxide oxidase processes (Douzou, 197la,b). When compound II reacted with indole 3-acetate, this compound was immediately regenerated without the appearance of any other intermediary compound. Moreover, indole 3-acetate in large excess induced the conversion of compound III into compound II. A study of reaction mechanisms of indole 3-acetate degradation by various peroxidases was recently carried out by Ricard and Job (1974) using low-temperature spectroscopic techniques. They obtained new data that made it possible to propose electronic mechanisms of reactions less speculative than those dependent upon data obtained under normal conditions of temperature. 

The ability of HRP to degrade the plant hormone indole-3-acetic acid (lAA) in the absence of hydrogen peroxide was noted as early as 1955 (136). Plant peroxidases are now known to be of major importance in the metabolism of lAA (137) (note that they are often referred to as indole acetic acid oxidases in the older literature). The mechanism of lAA oxidation by HRP C is complex and has been studied experimentally in great detail by several groups (23, 137). Reaction products include indole-3-methanol, indole-3-aldehyde, and 3-methylene oxin-dole, which is probably a nonenzymatic conversion product of indole-3-methylhydroperoxide. The most important developments in this area have been reviewed (23). 

DC031 Knypl, J. S., K. M. Chylinska, and M. W. Brzeski. Increased level of chloro-genic acid and inhibitors of indole-3-acetic acid oxidase in roots of carrot infested with the northern root-knot nematode. Physiol Plant Pathol 1975 6 51. 

Oxidase, p-indolyl-acetic acid Call Tiss Oxidase, indole-acetic acid Stem pith 584 Palmitic acid, methyl ester Lf, Rt, St, Bk,... 

Phenotypical isolates from purified water shall be characterized. Biochemical testing (such as oxidase test, urease test, catalase test, citrate test, coagulase test, and indole test) and commercial test kits (such as API tests) and reagents may be used for conformation of some unique isolates. 

The principal reason that DMT must be administer parenterally is its rapid and efficient metabolism. It can be oxidized to the N-oxide. It can be cyclized to b-carbolines, both with and without an N-methyl group. It can be N-dealkylated to form NMT and simple tryptamine itself. Best known is its oxidative destruction, by the monoamine oxidase system, to the inactive indoleacetic acid. There is a wild biochemical conversion process known for tryptophan that involves an enzymatic conversion to kynurenine by the removal of the indole-2-carbon. A similar product, N,N-dimethylkynuramine or DMK, has been seen with DMT, when it was added to whole human blood in vitro. 

A case in point. What happens when you put a methyl group on the two-position of the indole ring of a tryptamine. In the three examples, examples of the best studied tryptamines that were not active orally, they all became orally active. DMT, DET and 5-MeO-DMT, the three major parenterally-only active psychedelics, all blossomed into orally active compounds with the addition of a simple methyl group to that indole 2-position. As I had smugly argued, in the discussions of 2-Me-DMT, 2-Me-DET and Indapex, it is as if that bit of bulk got in the way of the destructive amine oxidases, and protected the molecule from its expected first-pass metabolic destruction. 

EXTENSIONS AND COMMENTARY In the 1960 s there was quite a bit of interest in a couple of pharmaceutical houses with the indole analogues of amphetamine. Both the alpha-methylated tryptamine (this compound, a-MT) and the alpha-ethylated homologue (a-ET, see its separate recipe) were found to be effective monoamine oxidase inhibitors, and both were clinically studied as potential antidepressants. The ethyl compound became a commercial drug, offered by the Upjohn Company as Monase, but now is considered to be without medical use and is a Schedule I drug. It is interesting that this methyl compound, a-MT was also a medically available antidepressant in the Soviet Union in the 1960 s and was sold under the name of Indopan, in 5 and 10 milligram tablets. 

Yu and Wang431 considered that indole-3-acetic acid exerts its stimulating effect on expansion growth by inducing the synthesis of the enzyme catalyzing the conversion of S-adenosylmethionine into ACC, a conclusion at variance with the suggestion of Vioque and coworkers432 that indoleacetic acid oxidase and its substrate (IAA) participate in the last reaction in the ethylene biosynthesis pathway, namely, the formation of ethylene from ACC. 

The harmala alkaloids harmaline (368 X = NH) and harmi.ne (369 X = NH) are active reversible inhibitors of monoamine oxidase (MAO). Benzo[ Jthiophene analogs of harmaline (368 X = S) and harmine (369 X = S), when tested in vitro as inhibitors of rat liver MAO, showed that (368 X = S) was 50 times more potent than harmaline, but (369 X = NH or S) were equivalent in potency. The replacement of the indolic nitrogen by sulfur greatly increased the lipid solubility of the molecule, which was reflected in the physiological disposition of the two analogs. 

The physiological effects of the kaempferol and quercetin derivatives are uncertain they inhibited indole-3-acetic acid oxidase in vitro they may induce dormancy, uncouple oxidative phosphorylation, stimulate plant... 

Catechol melanin, a black pigment of plants, is a polymeric product formed by the oxidative polymerization of catechol. The formation route of catechol melanin (Eq. 5) is described as follows [33-37] At first, 3-(3, 4 -dihydroxyphe-nyl)-L-alanine (DOPA) is derived from tyrosine. It is oxidized to dopaquinone and forms dopachrome. 5,6-Dihydroxyindole is formed, accompanied by the elimination of C02. The oxidative coupling polymerization produces a melanin polymer whose primary structure contains 4,7-conjugated indole units, which exist as a three-dimensional irregular polymer similar to lignin. Multistep oxidation reactions and coupling reactions in the formation of catechol melanin are catalyzed by a copper enzyme such as tyrosinase. Tyrosinase is an oxidase con-... 

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