4. Liver alcohol dehydrogenase (LADH) catalyzes a reversible, pH-dependent oxidation of an alcoholto an aldehyde according to the following reaction:LADHRCH2OH+NAD*RCHO+NADH+H*where NAD* and NADH are, respectively, the oxidized and reduced forms of the cofactor nicotin-amideadenine dinucleotide. While the reaction is actually a two-substrate reaction, it proceeds like a one-substrate reaction through a so-called compulsory-ordered ternary complex mechanism. It has beenshown through kinetic studies that, in the case of primary alcohols, the enzyme binds first the cofactorforming a binary enzyme-NAD* complex that then binds the second substrate, the alcohol, to form aternary enzyme-NAD*-substrate complex in which the oxidation of the alcohol proceeds with reductionof the cofactor.While the enzyme catalyzes oxidation of various steroids as well as ingested ethanol, it also catalyzesthe oxidation of methanol CH3OH, forming the extremely toxic product formaldehyde HCHO. Inges-tionof methanol, depending on the amount, results in blindness or death. Blindness results through damageto the retinol dehydrogenase in our retina. The remedy for methanol ingestion is to ingest or be givenintravenous ethanol. (Actually the patient becomes quite inebriated under these conditions.) Underthese conditions, ethanol acts as a competitive inhibitor of methanol oxidation, displacing it from LADH.This action provides sufficient time for the methanol to be harmlessly excreted by the kidneys.) If an individual has ingested 100 mL of methanol (a lethal dose), how much 100 proof(a) .whiskey (50% ethanol by volume) must he imbibe to reduce the activity of his LADH toward methanolto 5% of its original value? The adult human body contains ~40 L of aqueous fluids throughout whichingested alcohols are rapidly and uniformly mixed. The densities of ethanol and methanol are both 0.79g/cm3. Assume the KM values of LADH for ethanol and methanol to be 1.0 x 10-3 M and 1.0 x 10-2 M,respectively, and that Ki = KM for ethanol. Will the patient survive?%3D(b) ( . Why is the assumption Ki = KM for ethanol valid?

E + S <------> ES -------> E + P where, E = Alcohol dehydrogenase S =…

4. Liver alcohol dehydrogenase (LADH) catalyzes a reversible, pH-dependent oxidation of an alcohol to an aldehyde according to the following reaction: LADH RCH2OH NAD* RCHO NADH H* where NAD* and NADH are, respectively, the oxidized and reduced forms of the cofactor nicotin-amide adenine dinucleotide. While the reaction is actually a two-substrate reaction, it proceeds like a one- substrate reaction through a so-called compulsory-ordered ternary complex mechanism. It has been shown through kinetic studies that, in the case of primary alcohols, the enzyme binds first the cofactor forming a binary enzyme-NAD* complex that then binds the second substrate, the alcohol, to form a ternary enzyme-NAD*-substrate complex in which the oxidation of the alcohol proceeds with reduction of the cofactor.

4. Liver alcohol dehydrogenase (LADH) catalyzes a reversible, pH-dependent oxidation of an alcohol to an aldehyde according to the following reaction: LADH RCH2OH NAD* RCHO NADH H* where NAD* and NADH are, respectively, the oxidized and reduced forms of the cofactor nicotin-amide adenine dinucleotide. While the reaction is actually a two-substrate reaction, it proceeds like a one- substrate reaction through a so-called compulsory-ordered ternary complex mechanism. It has been shown through kinetic studies that, in the case of primary alcohols, the enzyme binds first the cofactor forming a binary enzyme-NAD* complex that then binds the second substrate, the alcohol, to form a ternary enzyme-NAD*-substrate complex in which the oxidation of the alcohol proceeds with reduction of the cofactor.

Chemistry & Chemical Reactivity

10th Edition

ISBN:9781337399074

Author:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel

Publisher:John C. Kotz, Paul M. Treichel, John Townsend, David Treichel

Chapter24: Biochemistry

Section: Chapter Questions

Problem 34GQ: The first step of the metabolic process known as glycolysis is the conversion of glucose to glucose-...

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Give the name of the enzyme that will most likely catalyze each of the following reactions: O CH3 - CH2 - OH + NAD+ → CH3 – C – H + NADH + H+ Ans. ___________________________________________ CH3 – C – COOH + R – CH – COOH → CH3 – CH – COOH + R – C – COOH O NH2 NH2 O HO – C – CH – CH2 – C – OH → HO – C – CH = CH – C – OH + H2O O OH O O O CO2 + CH3 – C – C – OH + ATP → HO – C – CH2 – C – C – OH + ADP + Pi O O O O…
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