Phosphoenolpyruvate Carboxykinase Activity in Grape Berries

Ruffner, H. P.; Kliewer, W. M.

doi:10.1104/pp.56.1.67

Cited by 52 publications

(32 citation statements)

References 22 publications

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“…Most measurements of PEPCK activity in plant extracts have been made by using either the carboxylation reaction or exchange reaction (9,11,12,14,18). Determinations of PEPCK activity by the PEPCK carboxylation reaction in crude plant extracts are complicated by the presence of PEP carboxylase (11,12).…”

Section: Discussionmentioning

confidence: 99%

Characterization of Phosphoenolpyruvate Carboxykinase from Panicum maximum

Ray¹,

Black²

1976

Plant Physiol.

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PEPCK has been characterized from several microorganisms and animals (1, 5-7, 9). However, only limited information is available on the characteristics of this enzyme in higher plants and most of this has been obtained using crude extracts (2, 10-14, 16, 18). In addition, the data on plant PEPCK are on either the exchange reaction or the ADP-dependent carboxylation reaction. Using either of these reactions to study PEPCK in relation to C4 photosynthesis is open to criticism since the proposed role of PEPCK is as a decarboxylase. The exchange reaction has been found to occur at rates much faster (3-to 30-fold) than either the carboxylation or decarboxylation reaction in animal tissue (7) Even though PEPCK is proposed as the decarboxylase in bundle sheath cells of certain C4 plants, no information is available on the characteristics of the ATP-dependent decarboxylation of OAA by the enzyme (12)(13)(14). This report presents data on the partial purification of PEPCK to remove PEP carboxylase using the C4 grass Panicum maxinum. The ATP-dependent decarboxylation reaction has been characterized and compared to the exchange reaction and the ADP-dependent carboxylation reaction.Phosphoenolpyruvate carboxykinase catalyzes the nucleotidedependent carboxylation of PEP2 to produce OAA in a reversible fashion as shown in equation 1. CO2 + ADP + PEP+&I% +OAA + ATP (1) In addition, PEPCK catalyzes a nucleotide-dependent exchange of CO2 into OAA (16,20).PEPCK has been proposed to act as a decarboxylase during photosynthesis in bundle sheath cells of specific plants which carry out C4 photosynthesis such as Panicum maximum. Through the action of PEPCK in these C4 plants, CO2 is released from OAA in the bundle sheath cells where the CO2 is refixed by the C3 cycle (3,12,14). In other C4 plants either a NADP+-or NAD+-dependent malic enzyme acts as the decarboxylase in bundle sheath cells. In all C4 plants the 4-carbon organic acids 1

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Section: Discussionmentioning

confidence: 99%

Characterization of Phosphoenolpyruvate Carboxykinase from Panicum maximum

Ray¹,

Black²

1976

Plant Physiol.

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“…L-Malic acid is degraded in grape berries via two pathways, mainly by the cytosolic NADP-malic enzyme (ME) (Ruffner et al, 1984) and, to a lesser extent, by the PEP carboxykinase (PEPCK) (see Fig. 2) (Ruffner and Kliewer, 1975). There is also evidence that the malate dehydrogenase (MDH), especially the mitochondrial iso-enzyme, plays a putative role in the degradation of L-malic acid in the grape berry.…”

Section: Figurementioning

confidence: 99%

“…L-Malic acid degraded via the NADP-malic enzyme fuels the required biosynthetic (in particular the provision of NADPH) and respiratory pathways (Ruffner et al, 1984), whereas a small percentage of L-malic acid (<5%) is converted back to phosphoenolpyruvate via MDH and PEPCK for glucose synthesis via gluconeogenesis (see Fig. 2) (Ruffner and Kliewer, 1975;Ruffner, 1982;Kanellis and Roubelakis-Angelakis, 1996 ).…”

Section: Figurementioning

confidence: 99%

Malic Acid in Wine: Origin, Function and Metabolism during Vinification

Volschenk

Vuuren

Viljoen-Bloom

2017

SAJEV

124

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The production of quality wines requires a judicious balance between the sugar, acid and flavour components of wine. L-Malic and tartaric acids are the most prominent organic acids in wine and play a crucial role in the winemaking process, including the organoleptic quality and the physical, biochemical and microbial stability of wine. Deacidification of grape must and wine is often required for the production of well-balanced wines. Malolactic fermentation induced by the addition of malolactic starter cultures, regarded as the preferred method for naturally reducing wine acidity, efficiently decreases the acidic taste of wine, improves the microbial stability and modifies to some extent the organoleptic character of wine. However, the recurrent phenomenon of delayed or sluggish malolactic fermentation often causes interruption of cellar operations, while the malolactic fermentation is not always compatible with certain styles of wine. Commercial wine yeast strains of Saccharomyces are generally unable to degrade L-malic acid effectively in grape must during alcoholic fermentation, with relatively minor modifications in total acidity during vinification. Functional expression of the malolactic pathway genes, i.e. the malate transporter (mae1) of Schizosaccharomyces pombe and the malolactic enzyme (mleA) from Oenococcus oeni in wine yeasts, has paved the way for the construction of malate-degrading strains of Saccharomyces for commercial winemaking.

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“…: 44 (114) 2824780; E-mail: r.leegood@sheffield.ac.uk plants, including partial decarboxylation of C4 acids in one group of C4 plants and in Crassulacean acid metabolism (CAM) plants such as the bromeliads (Leegood and Osmond 1990;Carnal et al 1993), as well as a role in the CO2-concentrating mechanism of certain algae (Holdsworth and Bruck 1977;Weidner and Ktippers 1982;Reiskind et al 1988;Reiskind and Bowes 1991). In addition, it plays a role in the ripening of grapes (Ruffner and Kliewer 1975).…”

Section: Introductionmentioning

confidence: 99%

Phosphoenolpyruvate carboxykinase from higher plants: Purification from cucumber and evidence of rapid proteolytic cleavage in extracts from a range of plant tissues

Walker

Trevanion

Leegood

1995

Planta

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Phosphoenolpyruvate carboxykinase (PEPCK) was purified 600-fold to homogeneity from the cotyledons of cucumber (Cucumis sativus L.) and a polyclonal antiserum raised. After sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) the purified preparation contained a single polypeptide of 62 kDa, consistent with previous studies of this enzyme in C4 grasses. Immunoblots of crude extracts showed that a form of PEPCK of approximately this molecular mass predominated in cucumber cotyledons and in a range of plant tissues (cotyledons of fat-storing seedlings, leaves of C4 and Crassulacean acid metabolism plants). However, when these tissues were extracted in the presence of SDS and the extracts analysed by immunoblotting, a larger polypeptide of 68-77 kDa was detected. Thus the enzyme generally measured in crude extracts is a smaller form which arises by rapid proteolysis. This phenomenon means that the native form of PEPCK has never been purified from plants nor its properties determined.

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Phosphoenolpyruvate Carboxykinase Activity in Grape Berries

Cited by 52 publications

References 22 publications

Characterization of Phosphoenolpyruvate Carboxykinase from Panicum maximum

Characterization of Phosphoenolpyruvate Carboxykinase from Panicum maximum

Malic Acid in Wine: Origin, Function and Metabolism during Vinification

Phosphoenolpyruvate carboxykinase from higher plants: Purification from cucumber and evidence of rapid proteolytic cleavage in extracts from a range of plant tissues

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