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Carboxymethylation of Cysteine Using Iodoacetamide/ Iodoacetic Acid

  • Alastair Aitken
  • Michèle Learmonth
Protocol
Part of the Springer Protocols Handbooks book series (SPH)

Abstract

If cysteine or cystine is identified in a protein it requires modification in order to be quantified. Thiol groups may be blocked by a variety of reagents including iodoacetic acid and iodoacetamide. Iodoacetate produces the S-carboxymethyl derivative of cysteine, effectively introducing new negative charges into the protein. Where such a charge difference is undesirable, iodoacetamide may be used to derivatize cysteine to S-carboxyamidomethylcysteine (on acid hydrolysis, as for amino acid analysis, this yields S-carboxymethylcysteine). The charge difference between these two derivatives has been utilized in a method to quantify the number of cysteine residues in a protein ([1], see  Chapter 89).

Keywords

Thiol Group Ammonium Bicarbonate Urea Solution Iodoacetic Acid Charge Difference 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Reference

  1. 1.
    Creighton, T. E. (1980) Counting integral numbers of amino acid residues per polypeptide chain. Nature 284, 487–488.PubMedCrossRefGoogle Scholar

Copyright information

© Humana Press Inc., Totowa, NJ 2002

Authors and Affiliations

  • Alastair Aitken
    • 1
  • Michèle Learmonth
    • 2
  1. 1.Division of Biomedical and Clinical Laboratory Sciences, Membrane Biology GroupUniversity of EdinburghScotland, UK
  2. 2.Department of Biomedical SciencesUniversity of EdinburghScotland

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