La glycéraldehyde‐3‐phosphate déshydrogénase du latex d'<i>Hevea brasiliensis</i>

Jacob, Jean-Louis; D'Auzac, Jean

doi:10.1111/j.1432-1033.1972.tb02528.x

Cited by 21 publications

(10 citation statements)

References 30 publications

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“…This is scarcely compatible with other major metabolisms such as synthesis of sucrose, and it is expected that GNR activity is modulated by metabolites. Some effectors have been detected (17)(18)(19).…”

Section: Nadph Product Inhibition Pattems Indicate Nadph As a Potentmentioning

confidence: 99%

“…dependent, EC 1.2.1.12) plus 3PGA2 kinase, and GNR (nonphosphorylating, EC 1.2.1.9). While NAD-triose phosphate dehydrogenase is of universal occurrence, the GNR is present in green cells and certain nonphotosynthetic plant tissues requiring sustained NADPH supply (4,18,24). Bamberger and co-workers (3) proposed that leaf GNR is a component of a shuttle transferring photosynthetic reducing power as NADPH to the cytoplasm.…”

Section: Nadph Product Inhibition Pattems Indicate Nadph As a Potentmentioning

confidence: 99%

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Glyceraldehyde 3-Phosphate:NADP⁺ Reductase of Spinach Leaves

Scagliarini

Trost²,

Valenti³

et al. 1990

Plant Physiol.

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The steady state kinetics of glyceraldehyde 3-phosphate:NADP+ oxidoreductase (GNR) (EC 1.2.1.9) have been investigated. The enzyme exhibits hyperbolic behavior over a wide range of substrate concentrations. Double-reciprocal plots are nearly parallel or distantly convergent with limiting Km values of 2 to 5 micromolar for NADP+ and 20 to 40 micromolar for Dglyceraldehyde 3-phosphate (G3P). The velocity response to NADP+ as the varied substrate is however sigmoidal if G3P concentration exceeds 10 micromolar, whereas the response to G3P may show inhibition above this concentration. This 'G3P-inhibited state' is alleviated by saturating amounts of NADP+ or NADPH. Product inhibition pattems indicate NADPH as a potent competitive inhibitor to NADP+ (K, 30 micromolar) and mixed inhibitor towards G3P, and 3-phosphoglycerate (3PGA) as mixed inhibitor to both NADP and G3P (K, 10 millimolar). The data, and those obtained with dead-end inhibitors, are consistent with a nonrapid equilibrium random mechanism with two altemative kinetic pathways. Of these, a rapid kinetic sequence (probably ordered with NADP+ binding first and G3P binding as second substrate) is dominant in the range of hyperbolic responses. A reverse reaction with 3PGA and NADPH as substrates is unlikely, and was not detected. Of a number of compounds tested, erythrose 4-phosphate (Ki 7 micromolar) and Pi (Ki 2.4 millimolar) act as competitive inhibitors to G3P (uncompetitive towards NADP ) and are likely to affect the in vivo activity. Ribose 5-phosphate, phosphoenolpyruvate, ATP, and ADP are also somewhat inhibitory. Full GNR activity in the leaf seems to be allowed only under high photosynthesis conditions, when levels of several inhibitors are low and substrate is high. We suggest that a main function of leaf GNR is to supply NADPH required for photorespiration, the reaction product 3PGA being cycled back to chloroplasts.

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Section: Nadph Product Inhibition Pattems Indicate Nadph As a Potentmentioning

confidence: 99%

Section: Nadph Product Inhibition Pattems Indicate Nadph As a Potentmentioning

confidence: 99%

Glyceraldehyde 3-Phosphate:NADP⁺ Reductase of Spinach Leaves

Scagliarini

Trost²,

Valenti³

et al. 1990

Plant Physiol.

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“…Shortly thereafter, Arnon et al (2) and Rosenberg and Arnon (31) reported the properties of a partially purified preparation of the enzyme from sugar beet 'This research was supported generously by the United States Atomic Energy Commission Grant AT (30-1) 3447 and by the National Science Foundation Grant GB 29126 X. leaves. Recently, Jacob and d'Auzac (17) have purified the enzyme from the latex of Hevea brasiliensis. In this laboratory, the partially purified enzyme from pea shoots was inhibited strongly by L-G3P (19).…”

mentioning

confidence: 99%

Nonreversible d-Glyceraldehyde 3-Phosphate Dehydrogenase of Plant Tissues

Kelly

Gibbs²

1973

Plant Physiol.

114

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Preparations of TPN-linked nonreversible D-glyceraldehyde 3-phosphate dehydrogenase (EC 1.2.1.9), free of TPN-linked reversible D-glyceraldehyde 3-phosphate dehydrogenase, have been obtained from green shoots, etiolated shoots, and cotyledons of pea (Pisum sativum), cotyledons of peanut (Arachis hypogea), and leaves of maize (Zea mays). The Plant tissues contain three enzymes for the oxidation of D-G3P' (12). Two of these catalyze a Pi-dependent, reversible oxidation of D-G3P to 1,3-diP-glycerate; one enzyme is DPNspecific and found in both photosynthetic and nonphotosynthetic tissues, while the other uses TPN and is most probably confined to the chloroplast. Both enzymes have been extensively studied (29). The third enzyme, which is TPN-specific, oxidizes D-G3P to glycerate-3-P in a reaction which does not require Pi and is not reversible. Evidence for this enzyme activity in green leaves was reported by leaves. Recently, Jacob and d'Auzac (17) have purified the enzyme from the latex of Hevea brasiliensis. In this laboratory, the partially purified enzyme from pea shoots was inhibited strongly by L-G3P (19). It is possible that the scarcity of reports on the enzyme is related to the presence of this inhibitor in commercial preparations of the substrate D-G3P.In the present investigation, the significance of this nonreversible D-G3P dehydrogenase to plant carbohydrate metabolism has been evaluated. A preparation of pea shoot enzyme, free of reversible Pi-dependent D-G3P dehydrogenase activity, has now been obtained, and the properties have been compared with those of the same enzyme partially purified from several other plant tissues. In addition, a relatively specific assay for the determination of the enzyme activity in cell-free extracts is described. Changes in the enzyme activity during the germination of peas and castor beans and the distribution of the enzyme in representative tissues were examined.The properties and in vivo localization of the three D-G3P dehydrogenases were compared, and the results indicate that, in some tissues, a major portion of triose-P oxidation may be mediated by the nonreversible enzyme.MATERIALS AND METHODS Materials. Pea (Pisum sativum L. var. Progress No. 9), maize (Zea mays L. var. Early Fortune), peanuts (Arachis hypogea L. var. Jumbo Virginia), and castor bean (Ricinus communis L.) were grown under natural lighting in a glasshouse at 16 to 18 C or in the dark at 22 C.The following chemicals and enzymes were obtained from the Sigma Chemical Company: ATP, dihydroxyacetone-P, DPN, D-erythrose-4-P, D-fructose-1 ,6-diP, DL-G3P, D-glycerate-3-P, P-glycolate, P-hydroxypyruvate, D-ribose-5-P, TPN, TPNH, G3P dehydrogenase, 3-P-glycerate kinase, and triose-P isomerase. Chloroacetol-P was a gift of Dr. F. C. Hartman through the courtesy of Dr. Louise Anderson. All chemicals were prepared as sodium salts at the recommended pH before use.L-G3P was prepared according to the method of Venkataraman and Racker (38). The D-G3P present in 0.65 mmole of DL-G3P was converted to glyce...

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“…The pea enzyme has a molecular weight of 140000 and an isoelectric point of 8.0 [l], whereas the values for the spinach enzyme are 600000 and 4.2 [3]. The third type of enzyme (EC 1.2.1.9) is specific for NADP', has no requirement for phosphate and catalyses the direct conversion of 3-phosphoglycerate to phosphoglyceric acid [5,6]. In marked contrast to the other two types of enzyme the reaction catalyzed is irreversible.…”

Section: _ _~mentioning

confidence: 99%