Phosphoenolpyruvate carboxylase
Phosphoenolpyruvate carboxylase (also known as PEP carboxylase, PEPCase, or PEPC; EC 4.1.1.31, PDB ID: 3ZGE) is an enzyme in the family of carboxy-lyases found in plants and some bacteria that catalyzes the addition of bicarbonate (HCO₃⁻) to phosphoenolpyruvate (PEP) to form the four-c…
What is the role of PEP carboxylase?
It absorbs wavelengths in only the blue and red parts of the visible spectrum. What is the role of PEP carboxylase in C4 and CAM plants? At what point in photosynthesis is the electromagnetic energy of light first converted into chemical energy?
What is photorespiration in plants?
A metabolic pathway that consumes oxygen and ATP, releases carbon dioxide, and decreases photosynthetic output. Photorespiration generally occurs on hot, dry, bright days, when stomata close and the O2/CO2 ratio in the leaf increases, favoring the binding of O2 rather than CO2 by rubisco. .
How does the Calvin cycle help C4 plants avoid photorespiration?
How does performing the Calvin cycle only in the bundle sheath cells help C4 plants avoid photorespiration? It helps by separating carbon fixation from the steps that generate O2.
What is the pathophysiology of photosynthesis?
A metabolic pathway that consumes oxygen and ATP, releases carbon dioxide, and decreases photosynthetic output. Photorespiration generally occurs on hot, dry, bright days, when stomata close and the O2/CO2 ratio in the leaf increases, favoring the binding of O2 rather than CO2 by rubisco.
What is the purpose of PEP carboxylase?
PEP carboxylase plays the key role of binding CO2 in the form of bicarbonate with PEP to create oxaloacetate in the mesophyll tissue.
What is PEP in biology?
Phosphoenolpyruvate (2-phosphoenolpyruvate, PEP) is the ester derived from the enol of pyruvate and phosphate. It exists as an anion. PEP is an important intermediate in biochemistry. It has the highest-energy phosphate bond found (−61.9 kJ/mol) in organisms, and is involved in glycolysis and gluconeogenesis.
What is the function of RuBisCO and PEP carboxylase?
RuBisCO is an enzyme involved in the first major step of carbon fixation, the process by which plants and other photosynthetic organisms transform atmospheric carbon dioxide into energy-rich molecules. PEP carboxylase is a mesophyll cell enzyme that catalyzes carbon fixation in C4 plants.
What is the function of phosphoenolpyruvate?
PEPCK should be viewed as a cataplerotic enzyme because it plays the important role of removing citric acid cycle anions for either the biosynthetic process or the subsequent complete oxidation of the these compounds to carbon dioxide in the citric acid cycle.
What enzyme does PEP inhibit?
PEP, a potent inhibitor of E. coli glucokinase, unlike most eukaryotic hexokinases, can act as a signal molecule controlling glucose uptake and glycolytic flux in cells.
Why is PEP high energy?
PEP is a high-energy compound because energy is released upon its hydrolysis, owing to the resonance stabilization of the inorganic phosphate released and the possible keto-enol tautomerization of its product, pyruvate.
Is PEP a sugar?
PEP group translocation, also known as the phosphotransferase system or PTS, is a distinct method used by bacteria for sugar uptake where the source of energy is from phosphoenolpyruvate (PEP). It is known to be a multicomponent system that always involves enzymes of the plasma membrane and those in the cytoplasm.
How many C are in a PEP?
…added to the three-carbon acid phosphoenolpyruvate (PEP) by an enzyme called phosphoenolpyruvate carboxylase. The product of this reaction is the four-carbon acid oxaloacetate, which is reduced to malate, another four-carbon acid, in one form of the C4 pathway.
Which photosystem accepts excited electrons from a reaction center chlorophyll and passes them to an electron transport?
In photosystem II , pheophytin accepts excited electrons from a reaction center chlorophyll and passes them to an electron transport chain.
What is the process of generating ATP from ADP and phosphate?
Photophosphorylation. The process of generating ATP from ADP and phosphate by means of a proton-motive force generated by the thylakoid membrane of the chloroplast during the light reactions of photosynthesis. effects of adding an uncoupler in photosynthesis.
How is O2 fixed to RuBP?
In photorespiration, O2 is fixed to RuBP by rubisco instead of CO2. The reactions that follow use ATP and result in the release of CO2, which decreases the overall rate of CO2 fixation and the production of sugar.
How is light energy converted to chemical energy?
Light energy is first converted to chemical energy when electrons are transferred from excited pigments to an electron carrier in a photosystem reaction center.
Which membrane generates ATP?
The process of generating ATP from ADP and phosphate by means of a proton-motive force generated by the thylakoid membrane of the chloroplast during the light reactions of photosynthesis.
Why do sugars take so much energy?
Because sugars store a great deal of potential energy, producing them takes a great deal of chemical energy.
Which end of the spectrum does chlorophyll a absorb?
Chlorophyll a can absorb well in both the violet/blue end of the spectrum and the orange/red end of the spectrum. Why then is ultraviolet light considered a very good source of energy for photosynthesis?
Which part of the leaf absorbs green light?
The chlorophyll in the leaves absorbs green light.
What happens when a plant runs out of water and converts stored sugar into water and CO2?
Photorespiration occurs when a plant runs out of water and converts stored sugar into water and CO2.
Which molecule reflects orange/red light away from chlorophyll a?
Chlorophyll b reflects orange/red light away from chlorophyll a.
What changes the shape of the leaves when struck by green light?
The chlorophyll in the leaves changes shape when struck by green light.