Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.4.1.1 (pyruvate carboxylase)
 1,516 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Activities of key enzymes of the Calvin cycle and C(4) metabolism, rates of CO(2) fixation, and the initial products of photosynthetic (14)CO(2) fixation were determined in the podwall, seed coat (fruiting structures), and the subtending leaf (leaf below a receme) of Brassica campestris L. cv ;Toria.' Compared to activities of ribulose-1,5-bisphosphate carboxylase and other Calvin cycle enzymes, e.g. NADP-glyceraldehyde-3-phosphate-dehydrogenase and ribulose-5-phosphate kinase, the activities of phosphoenol pyruvate carboxylase and other enzymes of C(4) metabolism, viz. NADP-malate dehydrogenase, NADP-malic enzyme, glutamate pyruvate transaminase, and glutamate oxaloacetate transaminase, were generally much higher in seed than in podwall and leaf. Podwall and leaf were comparable to each other. Pulse-chase experiments showed that in seed the major product of (14)CO(2) assimilation was malate (in short time), whereas in podwall and leaf, the label initially appeared in 3-PGA. With time, the label moved to sucrose. In contrast to legumes, Brassica pods were able to fix net CO(2) during light. However, respiratory losses were very high during the dark period.
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PMID:Photosynthetic Carbon Fixation Characteristics of Fruiting Structures of Brassica campestris L. 1666 21

Because in the phloem sap of maize (Zea mays L.) leaves a quarter of the total amino nitrogen can be found as alanine, the capacity of a de novo synthesis of alanine from 3-phosphoglycerate (3-PGA) was studied with isolated bundle sheath (BS) strands of maize. Inasmuch as these cells have retained their plasmodesmatic openings, it was possible to study the formation of alanine from 3-PGA when glutamate and ADP were being added. Alanine synthesis required the existence of the intact cell structure. From the formation of the intermediates, partially released to the medium, the activities of the enzymes of the reaction chain from 3-PGA to alanine could be measured in the intact cells. The results show that in the BS cells the rate of alanine production from pyruvate (0.5 micromole/minute per milligram BS chlorophyll) is more than sufficient to produce one-fourth of the assimilated nitrogen as alanine. As the activity of pyruvate kinase in intact bundle sheath cells in the light was found to be only 0.2 micromole/minute per milligram BS chlorophyll, it is concluded that in the light part of the conversion of 3-PGA to pyruvate may not occur via pyruvate kinase reaction, but via phosphoeno/pyruvate carboxylase, NADP-malate dehydrogenase, and NADP-malic enzyme in the mesophyll and BS cells.
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PMID:Alanine synthesis by bundle sheath cells of maize. 1666 62

Introduction of a C4 photosynthetic pathway into C3 rice (Oryza sativa) requires installation of a biochemical pump that concentrates CO2 at the site of carboxylation in modified bundle sheath cells. To investigate the feasibility of this, we generated a quadruple line that simultaneously accumulates four of the core C4 photosynthetic enzymes from the NADP-malic enzyme subtype, phosphoenolpyruvate carboxylase (ZmPEPC), NADP-malate dehydrogenase (ZmNADP-MDH), NADP-malic enzyme (ZmNADP-ME), and pyruvate phosphate dikinase (ZmPPDK). This led to enhanced enzyme activity and mild phenotypic perturbations but was largely neutral in its effects on photosynthetic rate. Measurements of the flux of 13CO2 through photosynthetic metabolism revealed a significant increase in the incorporation of 13C into malate, consistent with increased fixation of 13CO2 via PEP carboxylase in lines expressing the maize PEPC enzyme. However, there was no significant differences in labeling of 3-phosphoglycerate (3PGA) indicating that there was no carbon flux through NADP-ME into the Calvin-Benson cycle. There was also no significant difference in labeling of phosphoenolpyruvate (PEP) indicating that there was no carbon flux through PPDK. Crossing the quadruple line with a line with reduced glycine decarboxylase H-protein (OsGDCH) abundance led to a photosynthetic phenotype characteristic of the reduced OsGDCH line and higher labeling of malate, aspartate and citrate than in the quintuple line. There was evidence of 13C labeling of aspartate indicating 13CO2 fixation into oxaloacetate by PEPC and conversion to aspartate by the endogenous aspartate aminotransferase activity. While Kranz anatomy or other anatomical modifications have not yet been installed in these plants to enable a fully functional C4 cycle, these results demonstrate for the first-time a partial flux through the carboxylation phase of NADP-ME C4 metabolism in transgenic rice containing two of the key metabolic steps in the C4 pathway.
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PMID:A Partial C4 Photosynthetic Biochemical Pathway in Rice. 3317 34