Phosphoenolpyruvate carboxylase PEPC

Nonphotosynthetic COi fixation via phosphoenolpyruvate carboxylase (PEPC) can contribute a substantial proportion of carbon (>30%) for the biosynthesis of carboxylates in roots of P-deficient plants (Fig. 5) (11,82,101,111-113). Thus, PEPC-mediated COi fixation may be interpreted as an anaplerotic carbon... 

Bio-Research Products Inc., was founded in 1975, and specialized in the isolation, purification and characterization of enzymes and proteins. The company is well known for its production of wheat germ phosphoenolpyruvate carboxylase (PEPC). Currently, it is involved in finished goods and raw material production, through a biomedical contract. Bio-Research Products runs custom services on enzymes, proteins production, diagnostic assays, and other goods for industry, governments, or academia. Bio-Research Products, Inc. also markets a number of enzymes and associated products, and carries out custom synthesis projects. 

Phosphoenolpyruvate carboxylase (PEPC) of Thermus sp., was characterized and its mechanism of stabilization was studied by means of site-directed mutagenesis. A divergent sequence at a Gly-rich region of Thermus PEPC was revealed to contribute to the activity at hi temperature but not to the tolerance to the irreversible heat inactivation. 

Phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) catalyzes the reaction of phosphoenolpyruvate (PEP) with HC03 to form oxaloacetate (OAA) and orthophosphate in... 

Phosphoenolpyruvate carboxylase (PEPC) and pyruvate Pi dikinase (PPDK) play significant roles in the photosynthetic fixation of carbon in and CAM plants. PEPC catalyzes the fixation of atmospheric CO2 to phosphoenolpyruvate (1), and PPDK catalyzes the formation of phosphoenolpyruvate, the substrate for PEPC (2). 

Leaves were sampled at the end of the light period (e.g. for plants with a diurnal dark period) or under light (e.g. for plants grown under continuous light). The activities of phosphoenolpyruvate carboxylase (PEPC) and NADP-malic enzyme (ME) were assayed according to Holtum and Winter (4) with slight modifications. 

Phosphoenolpyruvate carboxylase (PEPC) pyruvic acid Mg"", Mn " oxaloacetate C4-plants (mais, sugar cane, sorghum, etc.)... 

Activity-levels of phosphoenolpyruvate carboxylase (EC 4.1.1.31, PEPC) and phosphoenolpyruvate carboxykinase (EC 4.1.1.49, PEPK) were examined with Rhodopseudomonas sp. No.7 grown photoanaerobically in an ethanol-bicarbonate and in an acetate medium. PEPC and PEPK were purified from cells grown under these conditions, and several characteristics of the enzymes were discussed in connection with photoheterotrophy of purple nonsulfur bacteria. 

Figure 1. Three-dimensional structure of phosphoenolpyruvate carboxylase from E. coli. a) Subunit structure of PEPC. b) The entire PEPC molecule.

Many monocots use the C4 photosynthetic pathway. CO2 in mesophyll cells is first combined with phosphoenolpyruvate (PEP) via the enzyme PEP carboxylase (PEPc) to make the molecule oxaloacetate (OAA), which has 4 carbon atoms (hence C4 ). The OAA is usually transformed into malate, which is transported into bundle sheath cells and cleaved to pyruvate and CO2 again. The pyruvate is recycled back into the mesophyll cells to reform PEP. Unlike mesophyll cells, the bundle sheath cells in C4 plants are able to concentrate CO2 (i.e., they are not very leaky), so that most of the CO2 is fixed, and less fractionation occurs in forming PGA. If bundle sheath cells were perfectly gas tight, there would be zero fractionation from Rubisco, whereas if the cells were completely permeable to CO2, the isotope fractionation from Rubisco would be —25%o. In reality, bundle sheath cells can exhibit some leakiness, so there can be some Rubisco discrimination, but far less than in mesophyl cells. 

Fig. 10.9. Role of malic acid in the production of energy (ATP) and the formation of different substrates in the grape (Ruffner, 1982b). MDH, malate dehydrogenase ME, malic enzyme PEPC, phosphoenolpyruvate carboxylase PEPCK, phosphoenolpyruvate carboxykinase...

Early attempts to increase SA production included the overexpression of the phosphoenolpyruvate carboxylase ppc, PEPC) and phosphoenolpyruvate carboxykinase ipck, PEPCK) genes, which are involved in CO2 fixation. These enzymes incorporate one molecule of CO2 to convert PEP into... 

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