Biochemistry
6th Edition
ISBN: 9781305577206
Author: Reginald H. Garrett, Charles M. Grisham
Publisher: Cengage Learning
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Chapter 14, Problem 5P
Answers to all problems are at the end οΓthis book. Detailed solutions are available in the Student Solutions Manual. Study Guide, and Problems Book.
Comparison of Emzymatic and Nonenzymatic Rate Constants
The for alkaline phosphatase—catalyzed hydrolysis of melhylphoiphate is approximately 14/sec at pH 8 and 25ºC. The rate constant for the uncatalyzed hydrolysis of methyl phosphate under the same conditions is approximately I0-15/sec. What is the difference in the free energies of activation of these two reactions?
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Biochemistry
Ch. 14 - Answers to all problems are at the end οΓthis...Ch. 14 - Answers to all problems are at the end οΓthis...Ch. 14 - Prob. 3PCh. 14 - Prob. 4PCh. 14 - Answers to all problems are at the end οΓthis...Ch. 14 - Prob. 6PCh. 14 - Prob. 7PCh. 14 - Answers to all problems are at the end οΓthis...Ch. 14 - Answers to all problems are at the end οf this...Ch. 14 - Answers to all problems are at the end οf this...
Ch. 14 - Answers to all problems are at the end of this...Ch. 14 - Answers to all problems are at the end οΓthis...Ch. 14 - Answers to all problems are at the end οΓthis...Ch. 14 - Prob. 14PCh. 14 - Prob. 15PCh. 14 - Prob. 16PCh. 14 - Prob. 17PCh. 14 - Prob. 18PCh. 14 - Answers to all problems are at the end οΓthis...Ch. 14 - Answers to all problems are at the end οΓthis...Ch. 14 - Answers to all problems are at the end οΓthis...Ch. 14 - Prob. 22PCh. 14 - Prob. 23PCh. 14 - Prob. 24PCh. 14 - Prob. 25PCh. 14 - Prob. 26P
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- Answers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. Quantitative Relationships Between Rate Constants to Calculate Km, Kinetic Efficiency (kcat/Km) and Vmax - VI The enzyme catalase catalyzes the decomposition of hydrogen peroxide: 2H2O22H2O+O2The turnover number (kcat) for catalase is 40,000,000 sec-1. The Km of catalase for its substrate H2O2 is 0.11 M. a. In an experiment using 3 nanomole/L of catalase, what is Vmax? b. What is v when [H2O2] = 0.75 M? c. What is the catalytic efficiency of catalase? d. Does catalase approach catalytic perfection?arrow_forwardAnswers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. Quantitative Relationships Between Rate Constants to Calculate Km, Kinetic Efficiency (kcat/Km) and Vmax - I Measurement of the rate constants for a simple enzymatic reaction obeying Michaelis-Menten kinetics gave the following results: k1=2108M1sec1k1=1103sec1k2=5103sec1a. What is Ks, the dissociation constant for the enzyme-substrate complex? b. What is Km, the Michaelis constant for this enzyme? c. What is kcat (the turnover number) for this enzyme? d. What is the catalytic efficiency (kcat/Km) for this enzyme? e. Does this enzyme approach kinetic perfection? (That is, does kcat/Km approach the diffusion-controlled rate of enzyme association with substrate?) f. If a kinetic measurement was made using 2 nanomoles of enzyme per mL and saturating amounts of substrate, what would Vmax equal? g. Again, using 2 nanomoles of enzyme per mL of reaction mixture, what concentration of substrate would give v = 0.75 Vmax? h. If a kinetic measurement was made using 4 nanomoles of enzyme per mL and saturating amounts of substrate, what would Vmax equal? What would Km equal under these conditions?arrow_forwardAnswers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. Quantitative Relationships Between Rale Constants to Calculate Km, Kinetic Efficiency (kcat/Km) and Vmax - II Triose phosphate isomerase catalyzes the conversion of glyceraldehyde-3-phosphate to dihydroxy-acetone phosphate. Glyceraldehyde3PdihydroxyacetonePThe Km of this enzyme tor its substrate glyceraldehyde-3-phosphate is 1.8 10-5 M. When [glyceraldehydes-3-phosphate] = 30 M, the rate of the reaction, v, was 82.5 mol mL-1 sec-1. a. What is Vmax for this enzyme? b. Assuming 3 nanomoles per mL of enzyme was used in this experiment ([Etotal]) = 3 nanomol/mL), what is kcat for this enzyme? c. What is the catalytic efficiency (kcat/Km) for triose phosphate isomerase? d. Does the value of kcat/Km reveal whether triose phosphate isomerase approaches catalytic perfection? e. What determines the ultimate speed limit of an enzyme-catalyzed reaction? That is, what is it that imposes the physical limit on kinetic perfection?arrow_forward
- Answers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. The enzyme alcohol dehydrogenase catalyzes the oxidation of ethyl alcohol by NAD+ to give acetaldehyde plus NADH and a proton: CHjCH3OH + NAD+ > C’H3CHO + NADH + H+ The rate of this reaction can be measured by following the change in pH. The reaction is run in 1-mL 10 m TRIS buffer at pH 8.6. If the pH of the reaction solution falls to 8.4 after 10 minutes, what is the rate of alcohol oxidation, expressed as nanomoles of ethanol oxidized per mL per sec of reaction mixture?arrow_forwardAnswers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. Assessing the Formation and Composition of Limit Dextrins Prolonged exposure of amylopectin to starch phosphorylase yields a substance called a limit dextrin. Describe the chemical composition of limit dextrins. and draw a mechanism for the enzyme-catalyzed rcactioa that can begin the breakdown of a limit dextrin.arrow_forwardAnswers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. Determining the Branch Points and Reducing Ends of Amylopectin A 0.2-g sample of amylopectin was analyzed to determine the fraction of the total glucose residues, that are branch points in the structure. The sample was exhaustively methylated and then digested, yielding 50-mol of 2,3-dimethylgluetose and 0.4 mol of 1,2,3,6- letramethylglucose. What fraction of the total residues are branch points? I low many reducing ends does this sample of amylopectin have?arrow_forward
- Answers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. Graphical Analysis of Negative Gooperativity in KNF Allosteric Enzyme Kinetics The KNF model for allosteric transitions includes the possibility of negative cooperativity Draw Lineweaver-Burk and Hanes-Woolf plots for the case of negative cooperatively m substrate binding. (As a point of reference, include a line showing the classic Michaelis-Menten response of v to [S].)arrow_forwardAnswers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. Phosphorylation of Proteins Introduces New Properties Phosphoproteins are formed when a phosphate group is esterified to an —OH group df a Ser, Thr, or Tyr side chain. At typical cellular pH values, this phosphate group bears two negative charges (— OPO32:_). Compare this side-chain modification to the 2U side chains of the Common amino acids found in proteins and comment on the novel properties that it introduces into side-chain possibilities.arrow_forwardAnswers to all problems are at the end οΓthis book. Detailed solutions are available in the Student Solutions Manual. Study Guide, and Problems Book. Consult the following reference (Samanta U. and Bahnson. B. J., 2008. Crystal structure of human plasma platelet-activating factor acetylhydrolase. Journal of Biological Chemistry 283:31617-3U624). consider the active-site structure of this enzyme in the Light of material in this chapter, and write a detailed mechanism for the PAF acetylhydrolase.arrow_forward
- Answers to all problems are at the end of this book Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. Solving the Sequence of an Oligopeptide From Sequence Analysis Data Analysis of the blood of a catatonic football fan revealed large concentrations of a. psychologic octapeptide. Amino acid analysis of this oclapeplide gave the following results: 2 Ala lArg 1 Asp 1 Mel 2 Tyr I Val 1NH/ The following facts were observed: Partial acid hydrolysis of the octapeptide yielded a dipeptide of the structure Chymolrypsin treatment of the octapeplide yielded two tetrapeptides, each containing an alanine residue. Trypsin treatment of one of the tetrapeptides yielded two dipeptides. Cyanogen bromide treatment of another sample of the same tetrapeplide yielded a tripeplideand free Tyr. N-lerminal analysis of the other tetrapeptide gave Asn. What is the amino acid sequence of this oclapeplide?arrow_forwardAnswers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. Solving the Sequence of an Oligopeptide From Sequence Analysis Data Amino acid analysis of ail oligopeptide seven residues long gave The following fads were observed: a. Trypsin treatment had no apparent effect. b. The phenylthiohydantoin released by Lid mini degradation was c. Brief chymotrypsin treatment yielded several products, including a dipeptide and a tetrapeptide. The amino acid composition of the tetrapeptide was Leu, Lyi. and Met. d. Cyanogen bromide treatment yielded a dipeptide, a tetrapeptide, and free Lys. What is the amino acid sequence of this heptapeptide?arrow_forwardAnswers to all problems are at the end of this book. Detailed solutions are available in the Student Solutions Manual, Study Guide, and Problems Book. Describe the Effects on cAMP and Glycogen Levels in Cells Exposed to Cholera Toxin Cholera toxin is an enzyme that covalently modifies the G-subunit of G proteins. (Cholera toxin catalyzes the transfer of ADP-ribose from NAD+ to an arginine residue in Gan ADP-ribosylation reaction.) Covalent modification of G� inactivates its GTPase activity. Predict the consequences of cholera to.vin on cellular cAMP and glycogen levels.arrow_forward
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