Indoleacetic acid oxidase

Hare, Robert C.

doi:10.1007/bf02858615

Cited by 117 publications

(41 citation statements)

References 90 publications

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“…It is evident, however, that the destruction of IAA resuilts in the formation of a ntimber of unstable intermediates leading to a produict that absorbs strongly at 254 and 247 mn. Althotugh these spectral changes were correlated with rates of IAA disappearance at steadv state (with purified IAA oxi(lase), and these changes cotldI be used to determine rates of the reaction, simple extrapolation in figuire 5 Literature Cited…”

Section: Discussionmentioning

confidence: 99%

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Partial Purification and Kinetics of Indoleacetic Acid Oxidase from Tobacco Roots

1966

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dase therefore behaves as a typical peroxidase, btit apparently is liniked to an aerobic system which produces H202 as a resuilt of the reactioni of free radical intermediates with 02 (23). Fuirther evideence for the peroxidase natuire of the enzyme was obtainied by Sttutz (21), who failed to separate IAA oxi(dase from peroxidase in preparationis from L'ptri1s by means of starch block electrophoresis.In attempts to correlate changes in IAA oxidlase activity in diseased tobacco tissuies (19) with the acctumtllation of phenolic inhibitors, it was nloted that the enzyme system from tobacco roots followved tuntustual kinetics. Highly active preparations did not exhibit the indtuction period typical of IAA oxidase from other souirces (17). It was felt that these resuilts couild be due to the simuiltanieouis action of IAA oxidase and a separate peroxi(lase in the system. It was also noted that fresh extracts from tobacco roots contained both IAA oxidase and peroxidase activities, but the ability to oxidize IAA disappearedl after the preparations were lyophilized or stored at -100 for several weeks, whereas the activity on polyphenols remained unaffected. The thermal inactivation points and the pH optima for both oxidations were different. \Vhereas these observations were not inconsistent with the view that a single enzyme with 2 separate centers for suibstrate attachment was involved, it seemed more 1200 www.plantphysiol.org on May 9, 2018 -Published by Downloaded from

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Section: Discussionmentioning

confidence: 99%

“…The existence of a iuiuclie enzyme or combination of enzymes capable of degradation of TAA has been questioned in the literature (5). This view has beein suipported b)y the fact that horseradish peroxidase, in the presciece of certain cofactors (Mn2 , phenols), catalyzes the reaction without addition of H2,O.…”

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confidence: 99%

Partial Purification and Kinetics of Indoleacetic Acid Oxidase from Tobacco Roots

1966

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“…Previous studies (2) (2) and appeared to be mediated by peroxidase (33), acting as an IAA oxidase (9,14).…”

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confidence: 93%

“…With our procedures, 14 distinct bands of peroxidase activity could be detected in gels after electrophoretic separation of extracts from both healthy and infected tissue. Four bands of low activity (bands [1][2][3][4] (Fig.…”

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confidence: 99%

The Role of Peroxidase Isozymes in Resistance to Wheat Stem Rust Disease

Seevers¹,

Daly²,

Catedral³

1971

Plant Physiol.

212

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In common with other disease situations, rust-resistant wheat leaves show a large increase in peroxidase activity during infection. Peroxidase isozymes from healthy or infected lines of wheat (Triticum aestivum L.) near isogenic for resistance and susceptibility to race 56 of Puccinia graminis tritici were separated by gel electrophoresis and the activity of each was estimated by photometric scanning. In order to ensure that the activity of isozymes observed on gels reflected the changes found in peroxidase enzymes assayed spectrophotometrically in extracts, a study was made of extraction procedures, substrates, and reaction conditions for both types of enzyme measurements. Of the 14 isozymes detected in both healthy and infected leaves, increases in only 1 (isozyme 9) were associated consistently with the development of resistant disease reaction at 20 C. Additional evidence was obtained to show that this isozyme can account for the increased peroxidase activity observed in extracts from resistant plants. When plants with high induced peroxidase activity due to resistance at 20 C were treated with ethylene or transferred to 25 C, they reverted to complete susceptibility. However, the disease-induced activity of isozyme 9 did not fall. The data suggest that, in this case, the association of peroxidase with resistance was a consequence of, not a determinant in, resistance.

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“…A characteristic featuire of IAA-oxidation by plant extracts is a lag in reaction (8). A lag of approximately 25 min was exlhibited in assays performed witlh a crude extract of cotton roots taken directly from the refrigerator (fig 1).…”

Section: Resultsmentioning

confidence: 99%

Stimulation of Indoleacetic Acid Oxidase and Inhibition of Catalase in Cotton Extracts by Plant Acids

Lane

King

1968

Plant Physiol.

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Abstract. Aotivity of indoleacetic acid oxidase in partially purified extracts from cotton is stimtulated by small amounts of malate, suocinate, fumarate, and other plant acids. The stimulation is apparently due to inhibition of catalase, which is detectable in certain preparations. The 4ag phase of indeleacetic acid oxidation by crude preparations is eliminated by steps in processing which oonceivably either denatures or dilutes catalse, or concentrates inhibitors to catalase.IAA-oxidase is inhibited int vitro by catalase (4, 5, 11), polyphenols (1, 3, 7, 14), various inhibitors and substrates of peroxidase (6,20), and by unidentified constituents of plant extracts (13,19). A number of phenols act in vitro either as inhibitors or co-factors, and a rather extensive literature provides a tacit support for the function of phenols in these roles in the plant.The possibility of regulation of IAA-oxidase by catalase in vivo has received surprisingly little emphasis. This has probably followed the observation of Goldacre et al. l(6) that phenols stimulate IAA-oxidase of peas in the absence of catalase. In efforts to partially purify IAA-oxidase from cotton roots, Lane (12) found that the protein (enzyme) fraction was separated from certain plant acids with a complete loss of IAA-oxidase activity. Addition of a small amount of any one of several organic acids restored activity completely.Noting that these same acids are inhibitors of catalase, we determined the effect of several acids on activities of catalase, peroxidase and IAA-oxidase in extracts of cotton. Results and DiscussionPlant Ciiltu(re. ,tmoles in 0.1 ml of water. Except whein noted, 2,4-dichlorophenol was not lused. All assays were conducted using 1 ml of enzyme soluttion, regardless of extent of concentration.Catalase. Decomposition of 110., was monlitored spectrophotometrically at 240 nm at 250, The reaction mixture contained 2 ml plant extract at appropriate dilution and 1 ml 0.059 M H.202 in 0,05 M phos,phate buffer, pH 7.0.For studies on the inhibition of catalase activitv by organic acids and 2,4-dichlorophenol, 3 tumoles of these compounds were added to the above in 0.1 ml. Controls contained 0.1 ml water. Initial rates of reaction were plotted froml optical density readings taken at 10 sec intervals for 2 mimi.Peroxidase. Appearanice of 8-aminoqu-i,noline oxidation prodtuct was monitored spectrophotometri-1699 www.plantphysiol.org on May 10, 2018 -Published by Downloaded from

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Indoleacetic acid oxidase

Cited by 117 publications

References 90 publications

Partial Purification and Kinetics of Indoleacetic Acid Oxidase from Tobacco Roots

Partial Purification and Kinetics of Indoleacetic Acid Oxidase from Tobacco Roots

The Role of Peroxidase Isozymes in Resistance to Wheat Stem Rust Disease

Stimulation of Indoleacetic Acid Oxidase and Inhibition of Catalase in Cotton Extracts by Plant Acids

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