Biochemistry Alanine Pyruvate

Write your Course ID# in the box below. NAME: For GradeScope, please write your FIRST and LAST name in CAPITAL letters WITHIN the box: I. MULTIPLE CHOICE (60 points; 2 points each)) Choose the BEST answer as requested in each question and writing the appropriate letter in the box at the left. 1. ________________/60 II. ________________/10 III. ________________/ 5 IV. ________________/10 V. ________________/15 TOTAL /100 Which of the following conversions requires more than one step? pyruvate 1. alanine 2. glutamate 3. aspartate 4. proline 5. phenylalanine A. B. C. D. E. 2. I. 1, 2, 1, 3, 2, 4, 1 and 4 and a-ketoglutarate oxaloacetate glutamate succinate and 4 and 5 and 5 4 5 Choose a correctly balanced equation for the degradation of CH3(CH2)9COOH via the b-oxidation pathway. A. B. C. CH3(CH2)9COOH + 5FAD + 5NAD+ + 6CoA-SH + 5H2O + ATP 5 Acetyl-CoA + 5FADH2 + 5NADH + 5H+ + CO2+ ADP + Pi CH3(CH2)9COOH + 5FAD + 5NAD+ + 6CoA-SH + 5H2O 5 Acetyl-CoA + 5FADH2 + 5NADH + 5H+ + CO2 CH3(CH2)9COOH + 4FAD + 4NAD+ + CoA-SH + 4H2O D. 4 acetyl-CoA + propionyl-CoA + 4FADH2 + 4NADH + 4H+ CH3(CH2)9COOH + 4FAD + 4NAD+ + 5CoA-SH + 4H2O + ATP E. 4 acetyl-CoA + propionyl-CoA + 4FADH2 + 4NADH + 4H+ + AMP + PPi CH3(CH2)9COOH + 4FAD + 4NAD+ + 5CoA-SH + 4H2O + ATP 4 acetyl-CoA + propionyl-CoA + 4FADH2 + 4NADH + 4H+ + ADP + Pi 3. Page 2 Urea synthesis in mammals takes place primarily in: A. B. C. D. E. 4. In the human genetic disease branched chain aminoaciduria (sometimes called maple syrup urine disease), the metabolic defect involves: A. B. C. D. E. 5. Histidine Glutamine Glutamate Aspartate AMP Glycine Threonine All of the above B & F All except C & D B & F & G All except C & D & E Serine or cysteine may enter the citric acid cycle as acetyl-CoA after conversion to: A. B. C. D. E. 8. ornithine aspartate glutamate adenine creatine Which metabolic intermediate provides free NH4+ for the production of urea from via the urea cycle? A. B. C. D. E. F. G. H. I. J. K. L. 7. transamination of an amino acid. oxidative decarboxylation. a deficiency of the vitamin niacin. uptake of branched chain amino acids into liver. synthesis of branched chain amino acids. Which of these directly donates a nitrogen atom for the formation of urea during the urea cycle? A. B. C. D. E. 6. skeletal muscle. liver. kidney. small intestine. brain. oxaloacetate. succinate. succinyl-CoA. pyruvate. propionate. How many of the 5 atoms in the imidazole ring of histidine end up in glutamate? A. B. C. D. E. F. G. 0 1 2 3 4 5 6 9. Page 3 If a person's urine contains unusually high concentrations of urea, which of the following diets has he or she probably been eating recently? A. B. C. D. 10. aspartate ATP ornithine succinate carbamoyl phosphate 30-34; much less than 30-34; much more than 30-34; about the same as Which of the following statements is false in reference to the mammalian synthesis of urea? A. B. C. D. 14. only and C-3 only only and C-4 In muscle, the oxidation of branched-chain amino acids can provide a significant amount of energy. The number of net ATP equivalents per mole of Ile is ______ when burned completely to CO2 and water and the energy used by the oxidative phosphorylation in the mammalian mitochondria. This is _____ as the amount of ATP from glucose. A. B. C. 13. C-1 C-1 C-3 C-4 C-3 Which substance is not involved in the production of urea via the urea cycle? A. B. C. D. E. 12. high carbohydrate, very low protein low carbohydrate, very high protein high fat, very low protein high fat, high carbohydrate, no protein Under some conditions, mitochondrial preparations can be made to convert added fatty acids almost quantitatively to acetoacetic acid. If palmitate (16:0) labeled with 14C in C-3 is added to such a preparation, and acetoacetate is isolated, where in acetoacetate will the label be found? A. B. C. D. E. 11. very very very very Krebs was a major contributor to the elucidation of the pathway involved. The precursor to one of the nitrogens of urea is aspartate. The process of urea production is an energy-yielding series of reactions. The amino acid arginine is the immediate precursor to urea. The human genetic disease phenylketonuria (PKU) can result from: A. B. C. D. E. F. G. H. I. J. inability to synthesize phenylalanine. inability to catabolize ketone bodies. inability to convert phenylalanine to tyrosine. production of enzymes containing no phenylalanine. deficiency of protein in the diet. deficiency in tertrahydrobiopterin All of the above C & F A & E A & C Page 4 15. Which of these amino acids is (are) both ketogenic and glucogenic? 1. 2. 3. 4. 5. A. B. C. D. E. 16. hydrolysis. deamination. oxidative deamination. reductive deamination. transamination. What is the name of this enzyme? It yields the Cys Ser N10-formyl-THF Ala Gly If an aerobic organism (e.g., the bacterium E. coli ) were fed each of the following four compounds as a source of energy, the energy yield from these substrates, in terms of ATP/mole, would be in the order: A. B. C. D. E. 19. 5 4 and 4 and 5 and 5 The degradation of tryptophan is both ketogenic and glucogenic. products acetyl-CoA, acetoacetyl-CoA, and ______. A. B. C. D. E. 18. 1 and 2 and 2, 3, 1, 3, 2, 4, Glutamate is metabolically converted to a-ketoglutarate and NH4+ by a process described as: A. B. C. D. E. 17. isoleucine valine histidine arginine tyrosine glucose > palmitate palmitate glucose > succinate alanine > succinate > > succinate > glucose > glucose > alanine > palmitate > succinate > glucose > alanine > palmitate (16:0) > alanine succinate > alanine palmitate Which of the following statements concerning the b oxidation of fatty acids is true? A. B. C. D. Two NADH are produced for each acetyl-CoA. The free fatty acid must be carboxylated in the b position by a biotindependent reaction before the process of b-oxidation commences. If electron transfer to oxygen were blocked as a result of cyanide poisoning, b-oxidation would also cease because the FADH2 generated in the process (by acyl-CoA dehydrogenase) could not be oxidized. About 1200 ATP molecules are ultimately produced per 20-carbon fatty acid oxidized. 20. A. B. C. D. E. 21. B. C. D. E. acyl-CoAs easily cross the mitochondrial membrane, but the fatty acids themselves will not. fatty acids cannot be oxidized by FAD unless they are in the acylcarnitine form. carnitine is required to oxidize NAD+ to NADH. acyl-carnitines readily cross the mitochondrial inner membrane, but acyl-CoAs do not. none of the above is true. If the 16-carbon saturated fatty acid palmitate is oxidized completely to carbon dioxide and water (via the b-oxidation pathway and the citric acid cycle), and all of the energy-conserving products are used to drive ATP synthesis in the mitochondrion, the net yield of ATP per molecule of palmitate is, in round numbers: A. 24. 5. ATP, coenzyme A, and hexokinase. ATP, carnitine, and coenzyme A. carnitine, coenzyme A, and hexokinase. ATP, carnitine, and pyruvate dehydrogenase. ATP, coenzyme A, and pyruvate dehydrogenase. Fatty acids are activated to acyl-CoAs and the acyl group is further transferred to carnitine because: A. 23. bound to hemoglobin. present at levels that are independent of epinephrine. carried by the protein serum albumin. freely soluble in the aqueous phase of the blood. nonexistent; the blood does not contain free fatty acids. Transport of fatty acids from the cytoplasm to the mitochondrial matrix requires: A. B. C. D. E. 22. Page 5 Free fatty acids in the bloodstream are: 3. B. 10. C. 25. D. 110. E. 1000. Which of the following is (are) true of the oxidation of one mole of oleate (a 18-carbon unsaturated fatty acid; 18:1) by the b-oxidation pathway, beginning with the free fatty acid in the cytoplasm? 1. 2. 3. 4. 5. 6. 7. Activation of the free fatty acid requires the equivalent of two ATP. Inorganic pyrophosphate (PPi) is produced. Carnitine functions as an electron acceptor. Eight moles of FADH2 are formed. Seven moles of FADH2 are formed. Eight moles of acetyl-CoA are formed. There is no direct involvement of NAD+. A. B. C. D. E. F. G. 1, 2, and 6 1, 3, and 5 1 and 5 only 5 only 1, 2, and 5 1, 2, and 4 1 and 2 only 6. 25. What is the correct order of function of the enzymes of b oxidation? 1. 2. 3. 4. A. B. C. D. E. 26. b-hydroxyacyl-CoA dehydrogenase thiolase enoyl-CoA hydratase acyl-CoA dehydrogenase 1, 3, 4, 1, 4, 2, 1, 3, 4, 2, 8 moles of acetyl-CoA are formed. 1 mole of ATP is needed. 8 moles of FADH2 are formed. The reactions occur in the mitochondria. AMP and PPi are formed. a-ketoglutarate. malate. succinyl-CoA. citrate. butyrate. In the disease sprue, vitamin B12 (cobalamin) is poorly absorbed in the intestine, resulting in B12 deficiency. If each of the following fatty acids were in the diet, for which one would the process of fatty acid oxidation be most affected in a patient with sprue? A. B. C. D. 29. 4 2 2 2 1 A fatty acid with an odd number of carbons will enter the citric acid cycle as acetyl-CoA and: A. B. C. D. E. 28. 3, 4, 1, 3, 3, Which of the following is not true regarding the oxidation of one mole of palmitate (16:0) by the b-oxidation pathway? A. B. C. D. E. 27. Page 6 CH3(CH2)14COOH CH3(CH2)12COOH CH3(CH2)11COOH CH3(CH2)10COOH Pyridoxal phosphate is a cofactor in this class of reactions: A. B. C. D. E. F. G. H. I. J. K. L. g-elimination. decarboxylation. reduction. desulfuration. transamination. b-elimination. methylation. all of the above E & C E & B A & B & E & F A & E & F & G 30. Page 7 Ketone bodies are formed in the liver and transported to the extrahepatic tissues mainly as: $ O CH3 C CH3 OH | CH2 | H CH3 OH | C COOH | H CH3 OH | C CH2 | H CH3 OH | C CH2 | H B. C. D. E. CH3 CH2 COOH COOH O C S-CoA II. TRUE-FALSE. (10 points) Place a "T" of "F" in the box on the left. No other answer will be accepted. 31. Vitamin B12 is used in enzymes that need the help of a free radical to perform the chemistry that they catalyze. 32. The 26S proteosome comes in two forms, a smaller form made of a 19S core plus other proteins, or a larger form made of a 20S core plus these other proteins, which in both forms regulate proteolysis, bind to ubiquinated proteins, and unfold the protein as the removes the ubiquitin proteins. 33. In animals, acetoacetate, beta-hydroxybutyrate, and acetone are derived from hydroxy-methylglutaryl-CoA, which comes exclusively from excess fatty acid degradation when sugar is unavailable. 34. Ubiquitin can be polymerized using the C-terminal carboxylate and lysine-11. When these polymers are attached to a lysine on any protein in the cell, it will be degraded by the proteosome. 35. Ketone bodies can arise from amino-acid degradation 36. If you had a deficiency of 2,4 dienoyl-CoA reductase there would be difficulty utilizing animal fat compared to utilizing plant oils. 37. Hormone-sensitive lipases in the adipose tissue are specific for hydrolysis of fatty acids only at certain positions of a triacylglyceride. Page 8 38. The turnover of cellular proteins destined for the lysosome are hydrolyzed by the same proteases as those destined for the proteosome. 39. The peroxisome has the same ability to degrade fatty acids to acetyl-CoA as does the mitochondria. However, the peroxisomes use the energy generated from betaoxidation to generate heat while exporting NADH and the acetyl-CoA to the mitochondria for ATP production. 40. The so-called P-450 enzymes in the liver are oxidases that are involved in metabolizing foreign compounds, such as drugs, for removal from the body. Physiologically, they also hydroxylate steroid hormones at various positions, which distinguish them from each other structurally and their resulting function. III. SHORT ANSWER. (5 points) Give a brief answer or fill in the blanks as directed to each problem or question below in the boxes. 41. How many ATP equivalents are derived from the complete oxidation of stearic acid (18:0)? How many ATP equivalents are derived from the complete oxidation of margaroleic acid (17:1 (∆9))? NOTE: In both cases start from the free fatty acid in the cytosol for your calculation.(3 pt) 42. If you had a patient who wanted to go on a high-protein diet, what FOUR vitamins would you look for in any concoction your patient wanted to take as a supplement? (2 pt) Page 9 IV. MECHANISMS. 43. (10 points) | | In the diagram draw arrows to indicate the movement of electrons for the decarboxylation of this glutamate-PLP aldimine intermediate. Mechanism #1: If the resulting quinoid intermediate is protonated at the stabilized carbanion, followed by hydrolysis of the PLP=AA Schiff base, name the resulting compound. Mechanism #2: If the resulting quinoid intermediate is NOT protonated at this stabilized carbanion, but rather the quinoid-Schiff base is hydrolyzed, name the resulting compound. Choose which of these two mechanisms is more likely based on which of these products could more readily (fewer steps) be used for energy production. Explain very briefly in the box by diagraming the pathway to a citric acid cycle intermediate. V. Page 10 PATHWAYS (15 points) Write out the pathway as requested. For each step give the name of the enzyme that catalyzes the reaction (NO abbreviations), any cofactors, co-substrates, substrates or products as indicated (abbreviations OK), and the name of each intermediate and their structures (including structures of starting and ending compounds; you can abbreviate phosphate as Pi, and a phosphoryl group by a circled "P"). 44. Draw the Urea Cycle from carbon dioxide and ammonia to urea. cofactors/ cosubstrates cofactors/ cosubstrates CO2 + NH4+ enzyme name structure & name + Pi structure & name + substrate enzyme name structure & name enzyme name structure & name cofactors/ cosubstrates cofactors/ cosubstrates enzyme name product structure & name structure & name enzyme name No. on Test Correct Answer 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 E D B B B J D D B B D C C H A C D C C C B D D E C C C C K D 31 32 33 34 35 36 37 38 39 40 T F F F T F T F T F 41 Stearate gives 9 acetyl-CoA = 90 ATP β-oxidation gives 8 each NADH (20 ATP) and FADH2 (12 ATP). Total is 122; minus 2 ATP for activation is 120. Margaroleate gives 7 acetyl-CoA (14C) (70 ATP) and 1 propiony-CoA (3C) (which goes to succinyl-CoA, but needs an ATP-dependent carboxylase; 20-1=19 ATP). β-oxidation gives 7 each NADH, or 7 x 2.5 = 17.5 ATP, but only 6 FADH2 (losing 1 for ∆9 double bond) = 9 ATP. Total is 70+19+17.5+9 = 115.5; minus 2 ATP for activation is 113.5. 42 Any of the following 4: B6 (pyridoxal, PLP) B12 (cobalamine) Folate (YHF, etc) Biotin B1 (thiamine, TPP) Riboflavin (FAD) Glutamate Dehydrogenase Niacin (NAD) Lipoic acid No. on Test Correct Answer 43 #1 4-amino butyrate #2 succinyl-semialdehyde Mechanism #2 is more easily converted to a citric acid cycle intermediate than #1. Pathway: Succinyl-semialdehyde is oxidized to succinate using NAD+, which is reduced to NADH. 43