Ascorbic Acid Oxidase in Cell Growth

Mertz, Dan

doi:10.1104/pp.39.3.398

Cited by 19 publications

(8 citation statements)

References 11 publications

(11 reference statements)

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“…This radical is generated by aseorbate (ASC) auto-oxidation or by an ascorbate oxidase (or peroxidase) activity. Both ASC and ascorbate oxidase have been detected in the apoplastic space of plant tissues [4, 14,19] including meristems [2] and root nodules [7].…”

Section: Inlroductionmentioning

confidence: 99%

The onset of cell proliferation is stimulated by ascorbate free radical in onion root primordia

Cabo

González‐Reyes

Navas

1993

Biology of the Cell

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Section: Inlroductionmentioning

confidence: 99%

The onset of cell proliferation is stimulated by ascorbate free radical in onion root primordia

Cabo

González‐Reyes

Navas

1993

Biology of the Cell

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“…Ohashi, 1988;Legendre et al, 1993). On the other hand, ascorbic acid, ascorbate oxidase, and ascorbate peroxidase have been suggested to occur in the plant cell wall (Mertz, 1964;Chichiricco et al, 1989). These latter components are likely to play a role in cross-linking reactions of cell wall polymers and could also be involved in oxygen radical scavenging and host-parasite interactions (Pene1 and Castillo, 199 1).…”

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The Role of Ascorbate Free Radical as an Electron Acceptor to Cytochrome b-Mediated Trans-Plasma Membrane Electron Transport in Higher Plants

1994

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“…A lower concentration ofascorbate inhibits cross-linking completely for a short time and then appears to be oxidized by the cell wall system, indicating that isolated cell walls maintain an oxidation potential. Ascorbate is normally synthesized by plant cells, and a wall-bound ascorbate oxidase has been reported with a possible role in cell growth control (17,22,23). It is attractive to speculate that a cell wallbound peroxidase-ascorbate oxidase system controls the redox potential of the wall and thus the rate of free radical phenolic cross-linking of wall polymers.…”

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confidence: 99%

Cross-Linking of Soluble Extensin in Isolated Cell Walls

Cooper¹,

Varner²

1984

Plant Physiol.

129

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The extension component of primary cell walls has generally been considered to be an intrinsily insoluble cell wall glycoprotein. Recent data have established that cell wail extensin is in fact secreted in a soluble monomeric form which slowly becomes insolubilized in the cell wail probably through the oxidative formation of Isodityrosine cross-liks.We now show that isolated cell walls from aerated root slices of Dawc carota have the capacity to insolubllize extensin through the formation of isodityrosine. This in vitro cross-linking is specific for the extension glycoproten, as other wall proteins are not cross-linked by the isolated wall system. Although extensin can be cross-linked in solution by peroxidase and H202, dityrosine and not isodityrosine is the phenolic crosslink formed. Wall-catalyzed cross-linking of soluble extension is inhibited by L-ascorbate, and both the initial rate and total extent of cross4iking are inhibited by acidic pH in the physiological range (pH 4 to 6). We suggest several mechanisms by which add might inhibit cross-nkn and propose that cytoplasmic factors ascorbatee and/or hydrogen ions) may regulate the solubility of extensin in vivo.Cell walls of dicotyledonous plants contain an insoluble glycoprotein component which is distinguished by its content of 4-hydroxyproline and has been given the name extensin (for review, see 7, 19). Despite suggestions that this integral wall polymer is important in growth control (4,17,25), disease resistance (10), and morphogenesis (1), the role of extensin in cell wall structure and function remains speculative and thus controversial (12,19).The biochemical characterization of extensin has proved especially difficult. For two decades it was generally believed that wall extensin is an intrinsically insoluble HRGP3 which could only be solubilized by proteolysis (17,18). Recently, we have shown, using aerated carrot root slices, that insoluble wall extensin is secreted into the cell wall as a soluble monomeric HRGP (5) which has been well characterized (28,29). This soluble extensin4 has a polycationic rod-like structure resembling bacterial agglutinins isolated from potato (20) extensin (5, 27). This insolubilization is inhibited in vivo by free radical scavengers and antioxidants (especially ascorbic acid), and is accompanied by the derivatization of tyrosine to IDT (5), a diphenyl ether-linked bityrosine recently characterized from plant cell wall hydrolysates and proposed to be responsible for covalently cross-linking extensin in the wall (5, 13).Understanding the manner in which extensin rods are assembled into insoluble wall extensin should provide new insight into the molelcular organization of plant cell walls. Because of the complexities associated with biochemical studies using in vivo systems, we have developed an in vitro system to study extensin cross-linking. Here we report the results of our studies. MATERIALS AND METHODSTissue Preparation. Large tap roots of Daucus carota were obtained from local merchants and stored at 4C...

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Ascorbic Acid Oxidase in Cell Growth

Cited by 19 publications

References 11 publications

The onset of cell proliferation is stimulated by ascorbate free radical in onion root primordia

The onset of cell proliferation is stimulated by ascorbate free radical in onion root primordia

The Role of Ascorbate Free Radical as an Electron Acceptor to Cytochrome b-Mediated Trans-Plasma Membrane Electron Transport in Higher Plants

Cross-Linking of Soluble Extensin in Isolated Cell Walls

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