Which of the following factors favour the oxygenase activity of RuBisCO ?
Question
Which of the following factors favour the oxygenase activity of RuBisCO ?
Solution
RuBisCO (Ribulose-1,5-bisphosphate carboxylase/oxygenase) is an enzyme that is involved in the first major step of carbon fixation in photosynthesis, but it also has an oxygenase activity. The factors that favor the oxygenase activity of RuBisCO are:
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High Oxygen Concentration: RuBisCO can catalyze the reaction with both CO2 and O2. When the concentration of O2 is high, the oxygenase activity of RuBisCO is favored.
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Low Carbon Dioxide Concentration: The carboxylase activity of RuBisCO is favored when the concentration of CO2 is high. Therefore, when the concentration of CO2 is low, the oxygenase activity is favored.
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High Temperature: The oxygenase activity of RuBisCO is favored at high temperatures. This is because the solubility of CO2 decreases with increasing temperature, which reduces the availability of CO2 for the carboxylase activity.
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Low Light Intensity: In low light conditions, the plant's stomata close to prevent water loss. This reduces the entry of CO2 into the leaf, which favors the oxygenase activity of RuBisCO.
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High Water Availability: When water is readily available, the plant's stomata are open, allowing more O2 to enter the leaf and favoring the oxygenase activity of RuBisCO.
Similar Questions
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Which enzyme is most abundantly found on Earth?(A) RuBisCO (B) Nitrogenase(C) Invertase (D) Catalase
Ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) is one of the most abundant enzymes on Earth. In carbon-fixing organisms, it consumes CO2 to carboxylate the sugar ribulose-1,5-bisphosphate (Ru1,5BP), and forms two molecules of 3-phosphoglycerate (3PG) as a product. The functional form of rubisco from the bacterium Rhodospirillum rubrum is a noncovalent homodimer composed of two 51 kDa monomers. Each subunit requires a magnesium ion (Mg2+) as a prosthetic group in the active site.Rubisco is often used as a model for protein folding studies. On their own, rubisco monomers typically cannot fold to completion and instead are trapped in a form known as a "kinetic intermediate." These kinetically trapped monomers cannot dimerize correctly and are prone to aggregation.Scientists interested in studying protein folding dynamics labeled the rubisco kinetic intermediate with a set of fluorophores known as a FRET (fluorescence resonance energy transfer) pair, with one fluorophore at the N-terminus and the other at the C-terminus. A FRET signal occurs when the emission spectrum of one fluorophore (the donor) overlaps with the excitation spectrum of the other (the acceptor). When the two fluorophores are sufficiently close to each other, the donor can transfer energy from the light it absorbs directly to the acceptor, causing the acceptor to emit light after the donor absorbs light.The GroEL/ES complex is a chaperone protein that binds and releases misfolded proteins, hydrolyzing ATP each time the protein is released. A misfolded protein may undergo multiple rounds of binding and release before adopting its correct conformation, or it may never fold correctly and instead be targeted for destruction (Figure 1).Figure 1 Representation of GroEL/ES-mediated protein foldingResearchers diluted the labeled kinetic intermediate into a refolding buffer in the presence or absence of 200 nM GroEL/ES and then monitored the FRET signal over time. They observed that under the conditions used, rubisco folding was first-order with respect to [unfolded rubisco] when GroEL/ES was present. The results are shown in Figure 2.Figure 2 FRET signal of labeled rubisco with and without GroELLin Z, Rye HS. Expansion and compression of a protein folding intermediate by GroEL. Mol Cell. 2004;16(1):23-34. Question 27Based on the molecular weight of a rubisco monomer, approximately how many amino acids are present in a rubisco dimer?A.460B.690C.920D.5100
Which of the following conditions is characterized by poor oxygenation of the blood?a) Jaundiceb) Cyanosisc) Pallord) Bronzing
Write a note on any two factors that are known to affect the activity of enzymes.
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