Pep Carboxylase
Pep Carboxylase - Related Videos
01:27
C4 Pathway and CAM
0 Views •
2019
Most plants use the C3 pathway for carbon fixation. However, some plants, such as sugar cane, corn, and cacti that grow in hot conditions, use alternative pathways to fix carbon and conserve energy loss due to photorespiration. Photorespiration is the process that occurs when the oxygen concentration is high. Under such conditions, the rubisco enzyme in the Calvin cycle binds O2 instead of CO2, which halts photosynthesis and consumes energy. C4 Pathway The C4 pathway is used by plants such as...
14:38
Establishment of Microbial Eukaryotic Enrichment Cultures from a Chemically Stratified Antarctic Lake and Assessment of Carbon Fixation Potential
0 Views •
Cited by 5 •
2012
Microbial eukaryotes are both a source of photosynthetically-derived carbon and top predatory species in permanently ice-covered Antarctic lakes. This report describes an enrichment culture approach to isolate metabolically versatile microbial eukaryotes from the Antarctic lake, Lake Bonney, and assesses inorganic carbon fixation potential using a radioisotope assay for Ribulose-1,5-bisphophate carboxylase oxygenase (RubisCO) activity.
01:28
Energy-releasing Steps of Glycolysis
0 Views •
2019
Glycolysis is divided into two phases based on whether energy is utilized or released. While the first phase consumes ATP, the second phase produces energy in the form of ATP and NADH. The energy is released over a sequence of reactions that turns G3P into pyruvate. The energy-releasing phase—steps 6-10 of glycolysis—occurs twice, once for each of the two 3-carbon sugars produced during steps 1-5 of the first phase. The first energy-releasing step—the 6th step of glycolysis —consists of two...
09:32
Direct Imaging of ER Calcium with Targeted-Esterase Induced Dye Loading (TED)
0 Views •
Cited by 60 •
2013
Targeted-esterase induced dye loading (TED) supports the analysis of intracellular calcium store dynamics by fluorescence imaging. The method bases on targeting of a recombinant Carboxylesterase to the endoplasmic reticulum (ER), where it improves the local unmasking of synthetic low-affinity Ca2+ indicator dyes in the ER lumen.
09:43
Protease- and Acid-catalyzed Labeling Workflows Employing 18O-enriched Water
0 Views •
Cited by 2 •
2013
Stable isotope labeling workflows employing 18O-enriched water (LeO-workflows) are versatile tools for quantitative and qualitative proteomics studies. In protease-assisted (PALeO) workflows, 18O-atoms are introduced by proteolytic cleavage and carboxyl oxygen exchange reactions mediated by proteases. In the acid-catalyzed (ALeO) workflow, 18O-atoms are introduced by carboxyl oxygen exchange at low pH.
FAQs
The reaction couples bicarbonate addition to phosphoenolpyruvate with the release of inorganic phosphate. This chemical sequence produces oxaloacetate, a four-carbon compound, rather than directly entering the Calvin cycle as the immediate product. The coupling links inorganic carbon capture with the formation of a metabolically useful intermediate in plant carbon metabolism.
PEP carboxylase captures carbon without directly using Rubisco, allowing carbon fixation to occur before the Calvin cycle in C4 and CAM plants. This separation is important because the enzyme can capture carbon under conditions where internal carbon dioxide is low. Carbon is therefore incorporated into an intermediate before Calvin-cycle processing.
The pathway becomes particularly valuable under high temperatures, drought, or low internal carbon dioxide. These conditions can limit the carbon available inside plant tissues, so initial capture through PEP carboxylase supports continued carbon fixation before the Calvin cycle. Its importance therefore reflects how plants maintain carbon metabolism under environmental stress.
In both C4 and CAM plants, PEP carboxylase acts at an early carbon-capture stage, generating oxaloacetate before carbon enters the Calvin cycle. A useful pathway sequence is initial bicarbonate incorporation, formation of the four-carbon intermediate, and subsequent delivery of fixed carbon toward Calvin-cycle metabolism. This arrangement separates initial capture from later carbon-processing reactions.
In microorganisms and other organisms, the enzyme can support anaplerotic reactions, which replenish metabolic intermediates consumed by cellular pathways. By restoring these compounds, PEP carboxylase contributes to pools needed for biosynthesis and energy production. Its significance therefore extends beyond photosynthetic carbon capture to the broader maintenance of metabolic balance.
Its activity can increase the availability of oxaloacetate-related metabolic intermediates for biosynthesis and energy production. In this context, the reaction functions as a replenishing route rather than solely as a photosynthetic carbon-capture step. Studying the enzyme in microorganisms and other organisms can therefore reveal how carbon input supports the continuity of central metabolism.