The muscle isozyme of lactate dehydrogenase is inhibited by lactate. Steady-state kinetic analysis yielded the following data, with lactate either absent orpresent at a fixed concentration.(a) Pyruvate is the substrate whose concentration is varied in one plot,NADH in the other. Identify each. Use an arrow and the appropriateletter (b, c, d, or e) to identify each of the following.(b) Reciprocal of Vmar for the uninhibited enzyme.(c) The line representing data obtained in the presence of lactate acting as acompetitive inhibitor with respect to the variable substrate.(d) The line representing data obtained in the presence of lactate acting as anoncompetitive inhibitor with respect to the variable substrate.(e) Reciprocal of KM in the presence of lactate acting as a competitiveinhibitor.(f) If KM for NADH is 2 x 10-5 M, then which of the following is the mostappropriate NADH concentration to use when determining KM forруruvate: 10 " M, 10 6 М, 10 М, 10 М, or 10> м?

An enzyme is a substrate that acts as a catalyst in living organisms, regulating the rate at which…

Answered: The muscle isozyme of lactate…

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter17: Metabolism: An Overview

Section: Chapter Questions

Problem 14P

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Using the ActiveModel for enoyl-CoA dehydratase, give an example of a case in which conserved residues in slightly different positions can change the catalytic rate of reaction.
The muscle isozyme of lactate dehydrogenase is inhibited by lactate. Steady-state kinetic analysis yielded the following data, with lactate either absent or present at a fixed concentration. (a) Pyruvate is the substrate whose concentration is varied in one plot,NADH in the other. Identify each. Use an arrow and the appropriate letter(b, c, d, or e) to identify each of the following.(b) Reciprocal of Vmax for the uninhibited enzyme.(c) The line representing data obtained in the presence of lactate acting as a competitive inhibitor with respect to the variable substrate.(d) The line representing data obtained in the presence of lactate acting as a noncompetitive inhibitor with respect to the variable substrate.(e) Reciprocal of KM in the presence of lactate acting as a competitiveinhibitor.(f) If KM for NADH is 2 x 10-5 M, then which of the following is the mostappropriate NADH concentration to use when determining KM for pyruvate: 10-7 M, 10-6 M, 10-5 M, 10-4 M, or 10-3 M?
The muscle isozyme of lactate dehydrogenase is inhibited by lactate.Steady-state kinetic analysis yielded the following data, with lactate eitherabsent or present at a fixed concentration. (a) Pyruvate is the substrate whose concentration is varied in one plot, NADH in the other. Identify each. Use an arrow and the appropriate letter (b,c,d,ore) to identify each of the following. (b) Reciprocal of Vmax for the uninhibited enzyme. (c) The line representing data obtained in the presence of lactate acting as a competitive inhibitor with respect to the variable substrate. (d) The line representing data obtained in the presence of lactate acting as a noncompetitive inhibitor with respect to the variable substrate. (e) Reciprocal of KM in the presence of lactate acting as a competitive inhibitor. (f) If KM for NADH is 2 x 10-5 M, then which of the following is the most appropriate NADH concentration to use when determining KM for pyruvate: 10-7 M, 10-6 M, 10-5 M, 10-4 M, or 10-3 M?M
The half-reactions involved in the lactate dehydrogenase (LDH) reaction and their standard reduction potentials are (see attached)). Calculate ΔG at pH 7.0 for the LDH-catalyzed reduction of pyruvate under the following conditions: (a) [lactate]/[pyruvate] = 1 and [NAD+]/[NADH] = 1. (b) [lactate]/[pyruvate] = 160 and [NAD+]/[NADH] = 160. (c) [lactate]/[pyruvate] = 1000 and [NAD+]/[NADH] = 1000. (d) Discuss the eff ect of the concentration ratios in Parts a–c on the direction of the reaction.
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A dialyzed pigeon liver extract will catalyze the conversion of acetyl-CoAto palmitate and CoASH if supplied with Mg2+, NADPH, ATP, HCO3-, andcitrate.(a) If H14CO3– is supplied, what compounds will become labeled (permanently or transiently) during the course of the reaction? In whatcompounds will 14C accumulate?(b) Explain the role of citrate in this reaction.

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