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) : 847-852.

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

Résumé : Phosphoribosylpyrophosphate synthetase (PRS; Ec 2.7.6.1) 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.

Mots-clés Agrovoc : Hevea brasiliensis, latex, enzyme, pyrophosphate, purification, technique analytique

Mots-clés complémentaires : Phosphatase

Classification Agris : F62 - Physiologie végétale - Croissance et développement

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)

Source : Cirad - Agritrop (https://agritrop.cirad.fr/389622/)

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