Indole acetic acid oxidase

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). 

From the cinnamic acids or phenyl propanoids described above, / -oxidation and truncation of side chains yields a variety of benzoic or simple phenolic acids [28], Rao et al., [22] identified gallic acid (18), gentisic acid (19), protocatechuic acid (20), />-hydroxybenzoic acid (21), oc-resorcyclic acid (22), vanillic acid (23) and salicylic acid (24) in C. arietinum and showed that overall, leaf content of all phenolic compounds was much greater than in roots and stem. They postulated that the production of these compounds may enhance the activity of indole acetic acid oxidase or may express antimicrobial properties when leached into the soil. However, Singh et al. [24] showed that the production of both 18 and 24 by C. arietinum was induced when treated by the culture filtrate of Sclerotium rolfsii along with the phenyl propanoids 14, 15 and 17 mentioned above. 

A.W. Galston and L.Y. Dalberg, "The Adaptive Formation and Physiological Significance of Indole-acetic acid oxidase," Am. J. Bot. 41 373 (1954). 

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,... 

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... 

Most tryptamine molecules are metabolized by the enzyme monoamine oxidase (MAO). MAO actually occurs in two different forms, MAO-A and MAO-B, which have preferences for different neurotransmitter molecules. MAO-A oxidizes the terminal amine of the tryptamines to an imine. This imine then undergoes nonenzymatic hydrolysis to an aldehyde that is subsequently converted to a carboxylic acid by a second enzyme, aldehyde dehydrogenase. The result is the conversion of the tryptamine into an acidic molecule, called an indole-3-acetic acid, which lacks psychoactivity. DMT is converted into indole acetic acid, whereas serotonin is converted into 5-hydroxyindole acetic acid (5-HIAA), and psilocin is converted into 4-hydroxy indole acetic acid. 

At physiological concentrations (10 M), flavonoids may either stimulate or inhibit lAA oxidase (an enzyme which regulates the amount of the plant-growth-regulating hormone indole acetic acid (lAA or auxin) activity in peas... 

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. 

Indolealkylamines. GC-MS methods applied in studies of the biochemical pharmacology of indoleamines parallel work on the catecholamines. SIM assays for serotonin (5-hydroxytryptamine), 5-methoxytryptamine, JV-acetylserotonin and melatonin (5-methoxy-N-acetyltryptamine) in rat pineal and brain tissue have been described [453,469]. Pentafluoro-propionyl derivatives and structural homologue standardisation were employed with detection limits in the subpicomole range. Estimation of central indoleamine turnover in man currently depends upon metabolite determination in CSF. Ion monitoring determination of indole-3-acetic acid [454] a metabolite of tryptamine, and isotope dilution assays for 5-hydroxyindoleacetic acid (5-HIAA) [455,458] have been reported. Serotonin is converted by central monoamine oxidase to 5-HIAA and the measurement of this metabolite, formerly by fluorimetry, is of interest in patients with CNS disorders [470]. GC-MS has also contributed to the identification of N,N-dimethyltryptamine in vitro [471] and isotope dilution technique has been applied to the measurement of this metabolite in control subjects and in psychiatric patients [472]. 

The indoleamines The indole of greatest significance in human metabolism is serotonin (5-hydro-xytryptamine (5-HT)) which is synthesized from tryptophan and metabolized by the monoamine oxidase system to 5-hydroxyindole acetic acid (5-HIAA). Serotonin is believed to play a significant role in maintenance of mood and many antidepressant drugs act via the serotoninergic receptor system. 

Indoleacetic acid (lAA) (17) is involved in many aspects of plant growth and development (Bonner and Varner, 1976 Kosuge and Sanger, 1986). This hormonal substance is derived in most plants by conversion of tryptophan to indole 3-pyruvic acid (15) (tryptophan amino transferase), decarboxylation to the indole 3-acetaldehyde (16) (indole pyruvate decarboxylase), and oxidation to indole 3-acetic acid (17) (indole acetaldehyde oxidase) (Fig. 7.6) (Goodwin and Mercer, 1983). 

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. 

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