Homework Help is Here – Start Your Trial Now!
Science
Chemistry
Question 2. While internal cysteine amino acid sidechains in proteins undergo oxidation to produce disulfide crosslinks that stabilize the protein structure after folding, solvent-exposed cysteine sidechains can remain in their reduced thiol form and serve as reactive nucleophiles (recall for instance Acyl Carrier Proteins involved in fatty acid biosynthesis or various oxidoreductase enzymes). The reactive thiol groups in proteins can be detected using Ellman's test, wherein the protein is reacted with a disulfide Ellman's reagent to form a new mixed disulfide and a 2-nitro-5-thiobenzoate (TNB) byproduct. Upon addition of base, TNB is deprotonated to form a dianion, which absorbs light in the visible region and can be detected using UV-Vis spectroscopy. Ellman's Reagent CO₂H -NO₂ internal disulfide crosslink O₂N- HO₂C SH solvent- exposed thiol UV Absorbance at 412 nm O₂N- -S TNB²- alkaline pH O₂N- SH HO₂C 2-nitro-5-thiobenzoate (TNB) -NO2 mixed disulfide CO₂H a) Provide a detailed arrow-pushing mechanism for the reaction of a thiol (you can use R-SH) with Ellman's reagent to produce a mixed disulfide and TNB. Ellman's Reagent R-SH + O₂N- HO₂C CO₂H -NO2 R-S Mixed disulfide CO₂H + -NO₂ O₂N- -SH HO₂C TNB Q2 Cont'd: b) Provide a reasonable explanation for why the TNB byproduct does not react further to undergo a similar type of disulfide exchange with the internal disulfide bond in the protein. -S + -NO₂ mixed disulfide CO₂H O₂N- -SH X “མ་ HO₂C TNB CO₂H NO2 SH S -NO2 CO₂H

Question 2. While internal cysteine amino acid sidechains in proteins undergo oxidation to produce disulfide crosslinks that stabilize the protein structure after folding, solvent-exposed cysteine sidechains can remain in their reduced thiol form and serve as reactive nucleophiles (recall for instance Acyl Carrier Proteins involved in fatty acid biosynthesis or various oxidoreductase enzymes). The reactive thiol groups in proteins can be detected using Ellman's test, wherein the protein is reacted with a disulfide Ellman's reagent to form a new mixed disulfide and a 2-nitro-5-thiobenzoate (TNB) byproduct. Upon addition of base, TNB is deprotonated to form a dianion, which absorbs light in the visible region and can be detected using UV-Vis spectroscopy. Ellman's Reagent CO₂H -NO₂ internal disulfide crosslink O₂N- HO₂C SH solvent- exposed thiol UV Absorbance at 412 nm O₂N- -S TNB²- alkaline pH O₂N- SH HO₂C 2-nitro-5-thiobenzoate (TNB) -NO2 mixed disulfide CO₂H a) Provide a detailed arrow-pushing mechanism for the reaction of a thiol (you can use R-SH) with Ellman's reagent to produce a mixed disulfide and TNB. Ellman's Reagent R-SH + O₂N- HO₂C CO₂H -NO2 R-S Mixed disulfide CO₂H + -NO₂ O₂N- -SH HO₂C TNB Q2 Cont'd: b) Provide a reasonable explanation for why the TNB byproduct does not react further to undergo a similar type of disulfide exchange with the internal disulfide bond in the protein. -S + -NO₂ mixed disulfide CO₂H O₂N- -SH X “མ་ HO₂C TNB CO₂H NO2 SH S -NO2 CO₂H

Chemistry
Chemistry
10th Edition
ISBN:9781305957404
Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Chapter1: Chemical Foundations
Section: Chapter Questions
Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...
See similar textbooks
icon
Related questions
Question
Question 2. While internal cysteine amino acid sidechains in proteins undergo oxidation to produce disulfide crosslinks that stabilize the protein structure after folding, solvent-exposed cysteine sidechains can remain in their reduced thiol form and serve as reactive nucleophiles (recall for instance Acyl Carrier Proteins involved in fatty acid biosynthesis or various oxidoreductase enzymes). The reactive thiol groups in proteins can be detected using Ellman's test, wherein the protein is reacted with a disulfide Ellman's reagent to form a new mixed disulfide and a 2-nitro-5-thiobenzoate (TNB) byproduct. Upon addition of base, TNB is deprotonated to form a dianion, which absorbs light in the visible region and can be detected using UV-Vis spectroscopy. Ellman's Reagent CO₂H -NO₂ internal disulfide crosslink O₂N- HO₂C SH solvent- exposed thiol UV Absorbance at 412 nm O₂N- -S TNB²- alkaline pH O₂N- SH HO₂C 2-nitro-5-thiobenzoate (TNB) -NO2 mixed disulfide CO₂H a) Provide a detailed arrow-pushing mechanism for the reaction of a thiol (you can use R-SH) with Ellman's reagent to produce a mixed disulfide and TNB. Ellman's Reagent R-SH + O₂N- HO₂C CO₂H -NO2 R-S Mixed disulfide CO₂H + -NO₂ O₂N- -SH HO₂C TNB
Transcribed Image Text:Question 2. While internal cysteine amino acid sidechains in proteins undergo oxidation to produce disulfide crosslinks that stabilize the protein structure after folding, solvent-exposed cysteine sidechains can remain in their reduced thiol form and serve as reactive nucleophiles (recall for instance Acyl Carrier Proteins involved in fatty acid biosynthesis or various oxidoreductase enzymes). The reactive thiol groups in proteins can be detected using Ellman's test, wherein the protein is reacted with a disulfide Ellman's reagent to form a new mixed disulfide and a 2-nitro-5-thiobenzoate (TNB) byproduct. Upon addition of base, TNB is deprotonated to form a dianion, which absorbs light in the visible region and can be detected using UV-Vis spectroscopy. Ellman's Reagent CO₂H -NO₂ internal disulfide crosslink O₂N- HO₂C SH solvent- exposed thiol UV Absorbance at 412 nm O₂N- -S TNB²- alkaline pH O₂N- SH HO₂C 2-nitro-5-thiobenzoate (TNB) -NO2 mixed disulfide CO₂H a) Provide a detailed arrow-pushing mechanism for the reaction of a thiol (you can use R-SH) with Ellman's reagent to produce a mixed disulfide and TNB. Ellman's Reagent R-SH + O₂N- HO₂C CO₂H -NO2 R-S Mixed disulfide CO₂H + -NO₂ O₂N- -SH HO₂C TNB
Q2 Cont'd: b) Provide a reasonable explanation for why the TNB byproduct does not react further to undergo a similar type of disulfide exchange with the internal disulfide bond in the protein. -S + -NO₂ mixed disulfide CO₂H O₂N- -SH X “མ་ HO₂C TNB CO₂H NO2 SH S -NO2 CO₂H
Transcribed Image Text:Q2 Cont'd: b) Provide a reasonable explanation for why the TNB byproduct does not react further to undergo a similar type of disulfide exchange with the internal disulfide bond in the protein. -S + -NO₂ mixed disulfide CO₂H O₂N- -SH X “མ་ HO₂C TNB CO₂H NO2 SH S -NO2 CO₂H
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 1 steps

SEE SOLUTIONCheck out a sample Q&A here
Blurred answer
Similar questions
  • SEE MORE QUESTIONS
Recommended textbooks for you
Chemistry
Chemistry
Chemistry
ISBN:
9781305957404
Author:
Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:
Cengage Learning
Chemistry
Chemistry
Chemistry
ISBN:
9781259911156
Author:
Raymond Chang Dr., Jason Overby Professor
Publisher:
McGraw-Hill Education
Principles of Instrumental Analysis
Principles of Instrumental Analysis
Chemistry
ISBN:
9781305577213
Author:
Douglas A. Skoog, F. James Holler, Stanley R. Crouch
Publisher:
Cengage Learning
Organic Chemistry
Organic Chemistry
Chemistry
ISBN:
9780078021558
Author:
Janice Gorzynski Smith Dr.
Publisher:
McGraw-Hill Education
Chemistry: Principles and Reactions
Chemistry: Principles and Reactions
Chemistry
ISBN:
9781305079373
Author:
William L. Masterton, Cecile N. Hurley
Publisher:
Cengage Learning
Elementary Principles of Chemical Processes, Bind…
Elementary Principles of Chemical Processes, Bind…
Chemistry
ISBN:
9781118431221
Author:
Richard M. Felder, Ronald W. Rousseau, Lisa G. Bullard
Publisher:
WILEY
SEE MORE TEXTBOOKS