Document Detail

Evidence for the involvement of cell wall peroxidase in the generation of hydroxyl radicals mediating extension growth.
MedLine Citation:
PMID:  12739149     Owner:  NLM     Status:  MEDLINE    
Hydroxyl radicals (*OH), produced in the cell wall, are capable of cleaving wall polymers and can thus mediate cell wall loosening and extension growth. It has recently been proposed that the biochemical mechanism responsible for *OH generation in the cell walls of growing plant organs represents an enzymatic reaction catalyzed by apoplastic peroxidase (POD). This hypothesis was investigated by supplying cell walls of maize ( Zea mays L.) coleoptiles and sunflower ( Helianthus annuus L.) hypocotyls with external NADH, an artificial substrate known to cause *OH generation by POD in vitro. The effects of NADH on wall loosening, growth, and *OH production in vivo were determined. NADH mediates cell wall extension in vitro and in vivo in an H2O2-dependent reaction that shows the characteristic features of POD. NADH-mediated production of *OH in vivo was demonstrated in maize coleoptiles using electron paramagnetic resonance spectroscopy in combination with a specific spin-trapping reaction. Kinetic properties and inhibitor/activator sensitivities of the *OH-producing reaction in the cell walls of coleoptiles resembled the properties of horseradish POD. Apoplastic consumption of external NADH by living coleoptiles can be traced back to the superimposed action of two enzymatic reactions, a KCN-sensitive reaction mediated by POD operating in the *OH-forming mode, and a KCN-insensitive reaction with the kinetic properties of a superoxide-producing plasma-membrane NADH oxidase the activity of which can be promoted by auxin. Under natural conditions, i.e. in the absence of external NADH, this enzyme may provide superoxide (O2*-) (and H2O2 utilized by POD for) *OH production in the cell wall.
Anja Liszkay; Barbara Kenk; Peter Schopfer
Related Documents :
47329 - Biosynthesis of yeast mannan. isolation of kluyveromyces lactis mannan mutants and a st...
17168519 - Lighting up the nascent cell wall.
15321799 - Role of cell walls in the bioaccessibility of lipids in almond seeds.
21764579 - Ph-control modes in a 5-l stirred-tank bioreactor for cell biomass and exopolysaccharid...
7749719 - Correlationships between enzymatic activity of lectins, putrescine content and chloropl...
6811119 - Glycogen and various other polysaccharides stimulate the formation of exolipase by pseu...
19960419 - Antiplasmodial and cytotoxic activity of khellactone derivatives from angelica purpurae...
11090139 - Mutations in herpes simplex virus glycoprotein d distinguish entry of free virus from c...
25286089 - Neuroprotection of a novel cyclopeptide c*hsdgic* from the cyclization of pacap (1-5) i...
Publication Detail:
Type:  Journal Article     Date:  2003-05-09
Journal Detail:
Title:  Planta     Volume:  217     ISSN:  0032-0935     ISO Abbreviation:  Planta     Publication Date:  2003 Aug 
Date Detail:
Created Date:  2003-08-07     Completed Date:  2004-01-12     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  1250576     Medline TA:  Planta     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  658-67     Citation Subset:  IM; S    
Institut für Biologie II der Universität, Schänzlestrasse 1, 79104 Freiburg, Germany.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Cell Wall / enzymology,  physiology
Cotyledon / drug effects,  enzymology,  physiology
Dose-Response Relationship, Drug
Helianthus / drug effects,  enzymology*,  growth & development
Hydrogen Peroxide / pharmacology
Hydroxyl Radical / metabolism*
Hypocotyl / drug effects,  enzymology,  physiology
Multienzyme Complexes / metabolism
NAD / pharmacology*
NADH, NADPH Oxidoreductases / metabolism
Peroxidase / metabolism*
Superoxides / metabolism
Zea mays / drug effects,  enzymology*,  growth & development
Reg. No./Substance:
0/Multienzyme Complexes; 11062-77-4/Superoxides; 3352-57-6/Hydroxyl Radical; 53-84-9/NAD; 7722-84-1/Hydrogen Peroxide; EC; EC 1.6.-/NADH oxidase; EC 1.6.-/NADH, NADPH Oxidoreductases

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

Previous Document:  Naïve impetus and Michotte's "tool effect": evidence from representational momentum.
Next Document:  Molecular and biochemical characterization of an aminoalcoholphosphotransferase (AAPT1) from Brassic...