Problem 2 The fundamental mechanism of many drugs is their ability to inhibit certain enzymes. One prominent example is salicylate (aspirin) which inhibits the catalytic action of glutamate dehydrogenase (GDH). The table below shows some experimental data where the GDH-salicylate system was investigated. a. Make an analysis of this data including the kinetic Vmax, KM and K₁. From the data, can you determine the type of inhibition? Substrate, mM 2.0 3.0 4.0 10.0 15.0 Product no inhibitor 141 181 215 315 372 per minute (nanomol) 6 mM inhibitor 89 120 150 258 314

Problem 2 The fundamental mechanism of many drugs is their ability to inhibit certain enzymes. One prominent example is salicylate (aspirin) which inhibits the catalytic action of glutamate dehydrogenase (GDH). The table below shows some experimental data where the GDH-salicylate system was investigated. a. Make an analysis of this data including the kinetic Vmax, KM and K₁. From the data, can you determine the type of inhibition? Substrate, mM 2.0 3.0 4.0 10.0 15.0 Product no inhibitor 141 181 215 315 372 per minute (nanomol) 6 mM inhibitor 89 120 150 258 314

Biology: The Dynamic Science (MindTap Course List)

4th Edition

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter6: Energy, Enzymes, And Biological Reactions

Section: Chapter Questions

Problem 1ITD

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Problem 1. Greco et al. have developed a regression curve fitting package in 1982 and tested it on Vp vs. [S] profiles of Hexosaminidase enzyme (see the figure below). The reactions rates were experimentally measured at various substrate concentrations in the presence or absence of an inhibitor. P-nitrophenyl-N-acetyl-ß-D- glucosaminide (NAG) is the substrate. 2-acetamido-2,4-dideoxy-4-fluoro-D-galactono-1,5-lactone (ADFGL) is the inhibitor. 1 0.9 0.8 -- No Inhibitor 0.7 - 0.2 mM Inhibitor 0.6 0.5 0.4 0.3 0.2 0.1 2 [S] (mM) Using the data given in the Figure, answer the following questions. A) Determine Vmax and Km of the reaction in the absence of inhibitor. B) Determine the inhibition type? C) Determine the equilibrium constant (K;) associated with the enzyme-inhibitor complex. V, (mM/s)
Homework 1 (a) The kinetic data given below are for the reaction catalyzed by prostaglandin endoperoxide synthase. Focusing here on the first two columns, determine the Vmax and Km of the enzyme. (b) Ibuprofen is an inhibitor of prostaglandin endoperoxide synthase. By inhibiting the synthesis of prostaglandins, ibuprofen reduces inflammation and pain. Us ing the data in the first and third columns of the table, determine the type of inhibition that ibuprofen exerts on prostaglandin endoperoxi' Rate of formation [Arachidonic acid] (mm) Rate of formation of PGG2 (mm/min) of PGG, with 10 mg/mL ibuprofen (mM/min) 0.5 23.5 16.67 1.0 32.2 25.25 1.5 36.9 30.49 41.8 44.0 2.5 37.04 3.5 38.91
Problems 14 and 15: some of the exponents are unclear. Here they are: 14. Calculate vi and the degree of inhibition caused by a competitive inhibitor under the following conditions:(a) [S]=2x10-3 Mand[I]=2x10-3 M(b) [S]=4x10-4 Mand[I]=2x10-3 M (c) [S]=7.5x10-3 Mand[I]=10-5 MAssume that Km = 2 x 10-3 M, Ki = 1.5 x 10-4 M and Vmax = 270 nmoles x liter-1 x min-1.The degree of inhibition is the percent of the uninhibited velocity reached in the presence of the inhibitor. 15. (a) What concentration of competitive inhibitor is required to yield 75% inhibition at a substrate concentration of 1.5 x 10-3 M if Km =2.9x10-4 M and Ki =2x10-5 M? (b)Towhatconcentration must the substrate be increased to reestablish the velocity at theoriginal uninhibited value?
(1) Enzy Matic, a Biochemistry student is studying the mode of inhibition of maleate to fumarase enzyme. Fumarase is the enzyme in the Kreb's cycle that converts fumarate to malate. He obtained the following kinetics data from her experiment: Velocity (mM/min) Inhibited 1.38 [S], mM Uninhibited 1.75 1.94 2.17 3.00 5.50 2.26 1.67 2.85 3.55 2.13 2.97 10.5 4.39 3.83
PROBLEMS 8.1 An enzyme-catalysed reaction was found to be affected by two inhibitors A and B. The following results were obtained at fixed total enzyme čoncentration: Substrate conc" Initial velocity (absorbance units per minute) (mmol l-) With 1 mmol I-B Uninhibited With 1 mmol l- A 0.684 50 20 1.08 0.653 0.468 10 1.43 1.01 0.649 0.476 0.374 0.311 5 1.02 0.363 0.798 0.657 3.3 0.296 2.5 0.250 2.0 0.549 Comment on these results. 8.2 The system investigated in problem 7.1 was investigated again under identical conditions but in the presence of an inhibitor, giving the following data: 40.0 6.67 10.0 156 20.0 Substrate conc" (mmol 1-1) Initial velocity (umol 1- min-1) 5.0 100 122 222 278 Determine the type of inhibition. If K, for this system is 2.9 mmol 1-', calculate the inhibitor concenträtion present.
Study problem 2 4. A coworker has just isolated a copper enzyme that catalyzes the conversion of oil sludge into soluble alcohols in the presence of O₂. There are two Cu atoms per protein, which consists of a single polypeptide chain. As the bioinorganic chemist on the project, you are given unlimited quantities of the protein for the purpose of determining the active site structure. You have at your disposal a number of physical techniques, including NMR and EPR spectrometers, a magnetic susceptometer, a Mössbauer instrument, an X-ray absorption beam line, a UV-VIS spectrophotometer, a Raman spectrometer, a magnetic circular dichroism instrument, but, alas, no X-ray diffractometer. You have time to complete measurements by only three techniques before you have to give a report to your colleague. Describe what measurements you would make, in what order you would make them to get the most out of time, what results you might expect, and how you would use this information to characterize…
PROBLEMS 8.1 An enzyme-catalysed reaction was found to be affected by two inhibitors A and B. The following results were obtained at fixed total enzyme čoncentration: Substrate conc" Initial velocity (absorbance units per minute) (mmol l-) With 1 mmol I-IB Uninhibited With 1 mmol I-1À 50 20 0.684 1.08 0.653 1.01 0.649 0.476 0.374 0.311 10 1.43 0.468 1.02 0.363 0.296 3.3 0.798 2.5 2.0 0.657 0.549 0.250 Comment on these results.
Accelerated Stability Testing Data Determine the expiration date of a drug product with the initial drug concentration of 50 mg/tablet using the following accelerated stability testing data: log Temp Rate Constant (1/min) 1/T (oC) 70 1.73E-05 80 3.38E-05 90 6.45E-05 Reaction Kinetics - Accelerated Stability Testing log In k Rate Constant Temp (oC) Temp (к) (1/min) (1/K) k 70 1.73E-05 80 3.38E-05 90 6.45E-05
Case Study: Enzyme Kinetics Data for new statin drug (inhibits HMG CoA reductase): ● ● I Substrate (UM) 0.5 1.0 1.5 2.5 3.5 || Rate of reaction (mm/min) 23.5 32.2 36.9 41.8 44 What are the Kms of the uninhibited and inhibited reactions? Rate of reaction in presence of 5.0 nM statin Using the above date, create a double-reciprocal (Lineweaver Burk) plot. What type of inhibition is shown by the new statin? What are the Vmax of the uninhibited and inhibited reactions? 16.67 25.25 30.49 37.04 38.91
KINETIC CONSTANT No Na2HPO4 25mM Na2HPO4 50mM Na2HPO4 Vmax nmol p-NP. Min- 20.3252 14.30615 17.30104 Km mM -0.819106 -0.46495 -0.352941 1. What does this suggest about the structure of the active side of the enzyme?
ent Page Form Combine Files Protect Flatten File Ch. 7] PROBLEMS Share 390% Enzymes-2.pdf Help + < Problems 125 (142/434) Capture the ronction: Add Bookmark 7.1 The following results were obtained for an enzyme-catalysed reaction Substrate concentration (mmol 1¹¹): 5.0 Initial velocity (umol l´¹ min¯¹): 147 Calculate Km and Vmax 6.67 10.0 20.0 182 233 323 125 40.0 400
In an enzyme kinetics study, three inhibitors resulted to the following results: Inhibitor ABC Inhibitor XYz Inhibitor PQR Without Inhibitor V 40.2 mM/sec 40.3 mM/sec 12.32 mM/sec 65.43 mM/sec max K 24.3 mM 28.5 mM 24.3 mM 15.7 mM b. What type of inhibitor is inhibitor PQR? Why do you say so?