phosphoenolpyruvate carboxylase

(redirected from PEP carboxylase)

phosphoenolpyruvate carboxylase

An enzyme that catalyses a two-step reaction: formation of carboxyphosphate and enolate form of pyruvate, and carboxylation of enolate with the release of phosphate. It replenishes oxaloacetate in the tricarboxylic acid cycle when operating in reverse. Phosphoenolpyruvate carboxylase is the recommended name for EC 4.1.1.31, orthophosphate:oxaloacetate carboxy-lyase (phosphorylating).

Phosphoenolpyruvate carboxylase  has also been used for:
(1) Phosphoenolpyruvate carboxykinase (GTP), EC 4.1.1.32 (GTP:oxaloacetate carboxy-lyase (transphosphorylating));
(2) Phosphoenolpyruvate carboxykinase (pyrophosphate), EC 4.1.1.38 (pyrophosphate:oxaloacetate carboxy-lyase (transphosphorylating)); and
(3) Phosphoenolpyruvate carboxykinase (ATP), EC 4.1.1.49 (ATP:oxaloacetate carboxy-lyase (transphosphorylating)).
References in periodicals archive ?
The first bypass reaction in gluconeogenesis is the conversion of pyruvate to phosphoenolpyruvate (PEP), involving the enzymes pyruvate carboxylase (PC) and PEP carboxylase (PCK).
One approach is to transform the key genes for C4 photosynthesis enzymes, such as PEP carboxylase (PEPC) (Hudspeth et al., 1992; Ku et al., 1999; Endo et al., 2008), NADP malic enzyme (NADP-ME) (Takeuchi et al., 2000; Tsuchida et al., 2001) and pyruvate orthophosphate dikinase (Fukayama et al., 2001; Wang et al., 2012) into C3 plants.
PEP carboxylase has been the subject of extensive experimental research in the last decades [1,2].[C.sub.4] plants (Maize) shows a mechanism to concentrate C[O.sub.2] at the site of PEP carboxylase [3] (E.C4.1.1.31) and there by overcome photorespiration.
Physical and kinetic properties of photosynthetic PEP carboxylase in developing apple fruit.
However, recent studies ensure that the activity of pyruvate carboxylase is prominent over PEP carboxylase (PetersWendisch, et al., 1997).
PEP carboxylase and malic enzyme play a vital role for channeling pyruvate pool, while C.
Here, the activity of the PEP carboxylase (25) was half of the PYR carboxylase, while the activity of malic enzyme was zero.
The key to efficiency in C4 metabolism is the initial enzyme that captures the bicarbonate, PEP carboxylase. The enzyme connects carbon to PEP (phosphoenolpyruvate), an important intermediate in respiration.
The advantage here is that a very efficient carbon-capturing enzyme, PEP carboxylase, is present in mesophyll cells to collect great quantities of C[O.sub.2] and feed it into bundle sheath cells surrounding the vascular system.
Instead of partitioning metabolites in space (between mesophyll and bundle sheath cells), CAM plants use PEP carboxylase to fix the carbon into malate, which is then stored until the next day, when the carbon is released and refixed in normal Calvin cycle metabolism.
In [C.sub.4] plants of the NADP-malic enzyme type (maize, Zea mays L., and sugarcane, Saccharinum spp.), PEP carboxylase fixes [CO.sub.2] into oxaloacetate, a four-carbon organic acid, which is then reduced to malate.