3. The ATP source for the glucose synthesis from lactate can be the conversion of lactate to pyruvate u subscquent oxidation of it to carbon dioxide and water. How many moles of lactate must be oxidized in the liver to CO, and H,0 to provide ATP for the synthesis of I mole of glucose from lactate? For answer: a) depict the diagrams of the lactate oxidation and gluconcogenesis from lactate; b) indicate the reactions produced and consumed ATP; c) name the hormones that regulate gluconeogenesis in the liver, and explain the mechanism hormonal signal transduction.

3. The ATP source for the glucose synthesis from lactate can be the conversion of lactate to pyruvate u subscquent oxidation of it to carbon dioxide and water. How many moles of lactate must be oxidized in the liver to CO, and H,0 to provide ATP for the synthesis of I mole of glucose from lactate? For answer: a) depict the diagrams of the lactate oxidation and gluconcogenesis from lactate; b) indicate the reactions produced and consumed ATP; c) name the hormones that regulate gluconeogenesis in the liver, and explain the mechanism hormonal signal transduction.

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter18: Glycolysis

Section: Chapter Questions

Problem 21P

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Figure 27.3 illustrates the response of R (ATP-regenerating) and U (ATP-utilizing) enzymes to energy charge. a. Would hexokinase be an R enzyme or a U enzyme? Would glutamine: PRPP amidotransferase, the second enzyme in purine biosynthesis, be an R enzyme or a U enzyme? b. If energy charge = 0.5: Is the activity of hexokinase high or low? Is ribose-5-P pyrophosphokinase activity high or low? c. If energy charge = 0.95: Is the activity of hexokinase high or low? Is ribose-5-P pyrophosphokinase activity high or low?
2. The overall result of CH,OH + 2 NAD+ + 2 NADH glycolysis can be summarized by the equation on the right in which HO the glucose origins of the carbon atoms in pyruvate are color coded. Show by writing the reactions catalyzed by aldolase and triose phosphate isomerase and num- bering the carbons why this is the fate of glucose carbon atoms in pyruvate. Indicate numbering of carbons in Glucose-6-Pi, Fructose-1,6-BisPi, enzyme products, and pyruvate. HO + 2 Pi 2 + 2 ATP > OH + 2 ADP (CH3 + 2 H20 Glucose Pyruvate
1. Outline the first round of lipid catabolism using a C18 saturated fatty acid. Indicate cofactors and type of chemistry that takes place. a. How much NADH, FADH2 and ACCOA are you getting from complete catabolism of this fatty acid? b. How many moles of ATP are you getting from the breakdown of this fatty acid? Keep in mind that in the mitochondria 1 mole FADH2 gives about 1.5 moles of ATP while 1 mole NADH yields about 2.5 moles of ATP.
2. (a) ( In contrast to the pyruvate dehydrogen- ase complex, the a-ketoglutarate dehydrogenase (aKGDH) complex is not up- or downregulated by phosphorylation or dephosphorylation. However, the complex exhibits cooperativity modulated by the presence of ADP, ATP, inorganic phosphate (Pi), and Ca2+, as illustrated by the diagram on the right for the bovine kidney enzyme complex. Note in the diagram how the addition of 10 μM Ca2+ shifts the affinity of the enzyme complex for aKG from 20 mM Pi/-Ca2+ to 20 mM Pi/+Ca2+. Calcium especially en- hances the cooperative influence of ADP and ATP. Using the expanded copy of the diagram at the end of the problem set, estimate the change in S0.5 (re- member that for allosteric enzymes S0.5 corresponds to KM of a nonallosteric enzyme) for the enzyme complex in the presence of 20 mM Pi/-Ca2+ and in the presence of 20 mM Pi/+Ca2+. Compare similarly the change in S0.5 for the enzyme in the presence of 20 mM Pi/-Ca2+ plus 1.6 mM ADP to the enzyme in the…
10. Glycogen, as the main storage form of glucosc, is an important energy reservoir. Describe the role of glycogen in providing the body with energy. To answer: a) write a scheme for glycogen mobilization, and oxidation of the end product to CO, and H,O; b) mark the reactions associated with ATP synthesis and ATP consumption in the scheme, calculate the oxidation energy yield of I mole of the final product resulting from glycogen breakdown; 1L An unconscious man with sions of alcobol poisonino was taken to the hosnital
4. During prolonged fasting and intense exercise, the product of fat breakdown in adipose tissue, glycerol, is one of the gluconeogenesis substrates. How can glycerol be involved in gluconcogenesis? How many moles of glycerol and ATP are required to synthesize I mole of glucose? To answer: 288 Chapter 6. Carbohydrate metabolism a) write a diagram for the glucose synthesis from glycerol and name the reactions occurring with ATP consumption; b) name the hormones that stimulate gluconcogenesis and describe the mechanism of signal transduction by these hormones; c) explain the role of the bifunctional enzyme in the regulation of gluconeoge- nesis.
1. The first step in the payoff phase of glycolysis is catalyzed by the enzyme glyceraldehyde 3-phosphate dehydrogenase, an enzyme that contains a nucleophilic cysteine playing a central role in the reaction. A) In the direction of gluconeogenesis, what reaction does this enzyme catalyze? AG° = -6.3 kcal/mol for this reaction in the direction of gluconeogenesis. Based on what you know about the substrates involved, provide two chemical reasons as to why the AGO of this reaction is negative.
2. Lactate dehydrogenase (LDH) catalyzes the reaction Ο ()) 0 NADH + H* NAD+ C=0 HO-C-H CH₁t Pyruvate lactate dehydrogenase CHa L-Lactate AG 25.1 kJ/mol which represents one of the metabolic fates of pyruvate, the end product of glycolysis. The positioning of the sub-strate pyruvate in the active site of lactate dehydrogenase is shown on the right. NADH (nicotinamide adenine dinu- cleotide) is a cofactor in the reaction and provides a hydride anion H (highlighted with light blue) through direct transfer to reduce the carbonyl group of pyruvate. (a) ( Gln 102 Arg109 NH2 NH Thr246 H₂C-C-OH HN NH H CHS H H H. His 195 NH Pyruvate N-(NADH) H H CH3 H HN H NH H₂C-C-CH₂ Пle250 Asp168 NH Arg171 ) Compare the mechanism of the LDH reaction, as implied by the diagram above, to that of a-chymotrypsin with respect to the oxyanion hole, conversion of the substrate carbonyl group having sp² hybridization to sp³ hybridization, the attacking nucleophile, and residues achoring the substrate in the active…
The enzyme is considered to be alan * ÇOO ÇOO Lactate dehydrogenase HO-C-H+ NAD C=0 + NADH + H CH: Pyruvate Lactate O Oxydoreductase O Isomerase O Hydrolase O Ligase O Dehydratase
6. Malate dehydrogenase catalyzes the following reversible reaction: COO- HO-C-H CH₂ COO™ L-Malate NAD+ y malate NADH + H+ dehydrogenase COO- 0=C CH₂ COO™ Oxaloacetate AG'° = 29.7 kJ/mol Malate + NAD+→NADH + H+ + oxaloacetate Calculate AG" and the ratio or products and reactants for the malate dehydrogenase reaction to proceed from left to right as shown. (The Faraday constant. 3, is 96.48 kJ/V-mol; RT(37°C)= 2.58kJ/mol) Steps: 1. Explain how you determined which molecule is an electron donor Malate and which is an acceptor NAD*. -2- 2. Calculate AED (write equation, then show calculations, for standard reduction potentials (E_values) see table in the posted lecture) 3. Calculate AG (write equation, then show calculations) 4. Calculate the ratio of products and reactants needed to for Malate + NAD+→→NADH + H+ + oxaloacetate reaction to proceed forward (write equation, then show calculations)
2. (a) List the number of NADH and FADH2 equivalents formed and the corresponding number of ATP equivalents generated by mitochondrial oxidation of one molecule of CH3(CH2) 12-COSCOA Number of NADH or FADH₂ formed Number of ATP ultimately formedª Enzyme catalyzing the oxidation step B Oxidation Acyl-CoA dehydrogenase B-Hydroxyacyl-CoA dehydrogenase Citric acid cycle Isocitrate dehydrogenase a-ketoglutarate dehydrogenase Succinyl-CoA synthetase Succinate dehydrogenase Malate dehydrogenase Total aThese calculations assume that mitochondrial oxidative phosphorylation produces 1.5 ATP per FADH2 oxidized and 2.5 ATP per NADH oxidized. GTP produced directly in this step yields ATP in the reaction catalyzed by nucleoside diphosphate kinase (p. 516).
1. Cyanide, oligomycin, and 2,4-dinitrophenol are all inhibitors of oxidative phosphorylation in mitochon- dria. Provide an explanation to the following conditions regarding these potent inhibitors. (a) Explain why adding cyanide to an active in vitro suspension of mitochondria blocks ATP synthesis. What happens to the rate of ATP synthesis when 2,4-dinitrophenol is added to this mitochon- drial suspension after it was treated with cyanide? (b) Explain why the rate of oxygen consumption decreases in an in vitro suspension of mito- chondria when oligomycin is added. What happens to the rate of oxygen consumption in this oligomycin- inhibited system after adding 2,4-dinitrophenol? Explain.