Immobilized and free apoplastic pectinmethylesterases in mung bean hypocotyl

The nature and the action pattern of apoplastic pectinmethylesterase (PME) isoforms were investigated in mung bean [Vigna radiata (L.) Wilzeck] hypocotyls. Successive extractions of neutral and alkaline PME isoforms present in hypocotyl native cell walls (referred to as PE1, PE2, PE3, PE4, with incr...

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Bibliographic Details
Published in:Plant physiology (Bethesda) 1994-11, Vol.106 (3), p.1151-1156
Main Authors: BORDENAVE, M, GOLDBERG, R
Format: Article
Language:English
Subjects:
actividad enzimatica
activite enzymatique
Agronomy. Soil science and plant productions
Biological and medical sciences
Cell walls
chemical composition
composicion quimica
composition chimique
culture media
Economic plant physiology
Enzymes
enzymic activity
esterasas
esterase
esterases
Fundamental and applied biological sciences. Psychology
Gels
hipocotilos
hypocotyle
Hypocotyls
isoenzimas
isoenzyme
isoenzymes
medio de cultivo
Metabolism
Metabolism and Enzymology
milieu de culture
Molecules
Nutrition. Photosynthesis. Respiration. Metabolism
pared celular
paroi cellulaire
pectinas
pectine
pectins
Plant cells
Plant physiology and development
Plants
Protein isoforms
Solubilization
vigna radiata
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Summary:The nature and the action pattern of apoplastic pectinmethylesterase (PME) isoforms were investigated in mung bean [Vigna radiata (L.) Wilzeck] hypocotyls. Successive extractions of neutral and alkaline PME isoforms present in hypocotyl native cell walls (referred to as PE1, PE2, PE3, PE4, with increasingly basic isoelectric points) revealed that solubilization of PE1, PE2, and PE4 did not induce any significant decrease in the cell-wall-bound PME activity. The in vitro de-esterification occurring when isolated cell walls were incubated with pectin resulted, then, from the activity of PE3. In addition, pH control of PME activity was shown to be much stronger for enzymes bound to cell walls, in their native state or reintroduced after solubilization, than for enzymes in solution. Mature cell walls showed much more activity than young cell walls, and were relatively enriched in two acidic PME isoforms missing in young cell walls. One acidic PME was also detected in the extracellular fluid. The acidic and neutral isoforms that could be easily transferred from their binding sites to their substrate might be those involved in the demethylation process developing along the mung bean hypocotyl.
ISSN:0032-0889
1532-2548
DOI:10.1104/pp.106.3.1151