Glucomannan-synthase activity in differentiating cells of Pinus sylvestris L

Particulate membrane preparations have been isolated from cambial cells, and from differentiating and differentiated xylem cells of the main stem of pine trees. These preparations synthesise a β1→4 glucomannan from guanosine 5′-diphosphate-mannose. The polysaccharide and the synthase have been chara...

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Bibliographic Details
Published in:Planta 1986-01, Vol.169 (4), p.564-574
Main Authors: Dalessandro, G. (Cambridge Univ. (UK). Dept. of Biochemistry), Piro, G, Northcote, D.H
Format: Article
Language:English
Subjects:
ACTIVIDAD ENZIMATICA
ACTIVITE ENZYMATIQUE
CAMBIUM
CELL DIVISION
CELL STRUCTURE
Cellular differentiation
DIVISION CELLULAIRE
DIVISION CELULAR
Entwicklung
Enzymaktivitaet
ENZYMIC ACTIVITY
ESTRUCTURA CELULAR
HEMICELLULOSE
HEMICELULOSA
Kambium
Mannans
METABOLISM
METABOLISME
METABOLISMO
Oligosaccharides
Paper chromatography
Particulate matter
Pine trees
Pinus
PINUS SYLVESTRIS
Polysaccharides
Solvents
Stamm
Stoffwechsel
STRUCTURE CELLULAIRE
Sugars
XILEMA
XYLEM
XYLEME
Zellstruktur
Zellteilung
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Summary:Particulate membrane preparations have been isolated from cambial cells, and from differentiating and differentiated xylem cells of the main stem of pine trees. These preparations synthesise a β1→4 glucomannan from guanosine 5′-diphosphate-mannose. The polysaccharide and the synthase have been characterized and the Km and Vmax for the synthase determined as 85 μM and 52.9 μM·min-1, respectively. The enzymic activity was inhibited by the addition of guanosine 5′-diphosphate-D-glucose so that the presence of an epimerase on the particulate fraction in conjunction with the synthase probably allowed the heteropolymer to be formed with the optimal ratio of the concentrations of the nucleoside-diphosphate sugar donors. No evidence for a polyprenyl-phosphate derivative as an intermediate during the polymer synthesis was obtained. Part of the control mechanism for the deposition of the large amounts of the glucomannan during the secondary thickening of the tracheids of the vascular system is by an increase in the amount of synthase activity at the endomembrane system of the cells. This probably occurs by an increase in the amount of enzyme which is modulated by gene regulation during differentiation.
ISSN:0032-0935
1432-2048
DOI:10.1007/BF00392108