Purification and characterization of phosphoribosylpyrophosphate synthetase from rubber tree latex

Gallois Richard, Prévôt Jean-Claude, Clément Anne, Jacob Jean-Louis. 1997. Purification and characterization of phosphoribosylpyrophosphate synthetase from rubber tree latex. Plant Physiology (115) : pp. 847-852.

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Autre titre : Purification et caractérisation de la phosphoribosylpyrophosphate synthétase à partir du latex d'hévéa

Abstract : Phosphoribosylpyrophosphate synthetase (PRS; Ec from #Hevea brasiliensis# Müll. Arg. latex was located in the cytosol. After purification, its apparent molecular weight under nondenaturing conditions was estimated at 200,000 + or - 10,000; a single band at 57,000 + or - 3,000 was detected after sodium dodecyl sulfate. Polyacrylamide gel electrophoresis. The enzyme seemed to be a homotetramer. Its affinity constants were estimated at 200 + or - 30 PM Dr adenosine triphosphate and 40 + or - 2 PM for ribose.5.phosphate . The purified enzyme proved to be functional in a paraphysiological medium (cytosol deproteinized by ultrafiltration). Optimum pH was 7.5 in buffer and 6.5 in a paraphysiological medium. No PRS activity vas detected in the absence of the Mg2+ ion. Of the numerous compounds tested, only Mn2+, phosphoribosylpyrophosphate, and inorganic phosphate affected the enzymatic reaction. Mn2+ (inhibitor constant = 20 PM) and phosphoribosylpyrophosphate (inhibitor constant = 30 PM) were inhibitors. PRS responded allosterically (Hill's coefficient = 2.3) to ribulose-5-phosphate in the presence of physiological concentration of inorganic phosphate (10 mM). These results are set in the physiological context of laticifers. (Résumé d'auteur)

Mots-clés Agrovoc : Hevea brasiliensis, Latex, Enzyme, Pyrophosphate, Purification, Technique analytique

Mots-clés complémentaires : Phosphatase

Classification Agris : F62 - Plant physiology - Growth and development

Auteurs et affiliations

  • Gallois Richard, CIRAD-CP-HEVEA (FRA)
  • Prévôt Jean-Claude, CIRAD-CP-HEVEA (FRA)
  • Clément Anne, CIRAD-CP-HEVEA (FRA)
  • Jacob Jean-Louis, CIRAD-CP-AGRONOMIE (FRA)

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