The following questions refer to the mitochondrial enzyme MALATE DEHYDROGENASE.
What is the chemical reaction, within the citric acid cycle, that is catalyzed by malate dehydrogenase, and which substrates, products, and/or cofactors are involved?
The reaction from the previous question is classified as a dehydrogenation, which means that the reaction represents a(n) _______________ wherein ________________.
a. oxidation reaction; malate loses electron(s)
b. oxidation reaction; malate gains electron(s)
c. reduction reaction; malate loses electron(s)
d. reduction reaction; malate gains electron(s)
e. hydrolysis reaction; malate loses hydrogen(s)
The ΔG'° for the chemical reaction catalyzed by malate dehydrogenase is +29.7 kJ/mol. Under standard biochemical conditions, is this reaction exergonic, endergonic, or close to equilibrium? Under these conditions, in which direction would this chemical reaction be expected to proceed?
Under typical cellular conditions of glycolysis and the citric acid cycle, does the malate dehydrogenase reaction represent a reversible catalytic step or an essentially irreversible step? Based on this answer, is the actual ΔG expected to be greater than, less than, or about equal to the ΔG'°? Why?
Within the context of the citric acid cycle the dehydrogenation of malate proceeds to the right (i.e. formation of oxaloacetate is favored). Why is this is so, and what other reactions or substrates/products of the TCA cycle are important here?
When gluconeogenesis is favored (and glycolysis is downregulated), describe the chemical reaction that is catalyzed by malate dehydrogenase. Under such conditions, is the formation of oxaloacetate or malate favored? Explain why the reaction proceeds in the direction you describe.© BrainMass Inc. brainmass.com October 16, 2018, 8:12 pm ad1c9bdddf
Malate dehydrogenase is a key enzyme of kreb cycle. It catalyzes the formation of NADH2. In malate shuttle, on other hand, extramitochondrial NADH is oxidized by OAA by the action of the cytoplasmic malate dehydrogenase to yield malate. It enters into the mitochondria via malate - succinate carrier and is oxidized to OAA by the action of the action of the intramitochondrail malate dehydrogenase. Here malate shuttle is reversible reaction and can function in either direction
Molecular Mechanisms for Competitive & Noncompetitive Inhibition
Please help me with ten of the following questions. See the attached document for proper formatting.
1. Distinguish the molecular mechanisms for competitive and noncompetitive inhibition.
2. Suggest a mechanism by which some enzymes can be partially protected from thermal decomposition by high substrate concentration.
3. See the attached file.
4. Describe, in your own words, the mechanism for chymotrypsin. Show how the amino acid residues of the active site participate in the reaction.
5. Adults engaged in strenuous physical activity require an intake of about 160g of carbohydrate daily but only about 20 mg of niacin for optimal nutrition. Given the role of niacin in glycolysis, how do you explain the observation?
6. Explain how ATP provides energy to reactions. Give an example.
7. Isocitrate dehydrogenase is found only in the mitochondrion, but malate dehydrogenase is found in both the cytosol and mitochondrion. What is the role of cytosolic malate dehdrogenase?
8. a. Draw the chemical reaction of ubiquinone that is important in electron transport. Use electron-pushing arrows to show what is happening.
b. What is the function of ubiquinone's isoprenoid tail?
9. Explain how carrots provide something that is essential for vision, and explain how this works biochemically.
10. How do vitamins protect against ROS (reactive oxygen species)? Give at two examples of such vitamins, including reaction chemistry. What is the major source of ROS in cells?
11. In your own words, explain how a pH gradient can be used to drive ATP synthesis.
12. Individuals with a thiamine-deficient diet have relatively high levels of pyruvate in their blood. Explain this in biochemical terms.
13. 2,4-DNP is a proton ionophore, allowing protons to diffuse across the mitochondrial membrane. 2,4-DNP was briefly used as a diet drug, but its use was discontinued because of associated fatalities. Explain why this chemical dramatically decreases the energy yield from glucose metabolism.View Full Posting Details