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Modification of Tryptophan with 2-Hydroxy-5-Nitrobenzylbromide

  • Dan S. Tawfik
Protocol
  • 120 Downloads
Part of the Springer Protocols Handbooks book series (SPH)

Abstract

2-Hydroxy-5-nitrobenzylbromide, Koshland’s reagent (1), reacts rapidly and under mild conditions with tryptophan residues. At low pH (<7.5) this reagent exhibits a marked selectivity for tryptophan; under more basic pH or at higher reagent concentrations, cysteine, tyrosine, and even lysine residues can be modified as well (see Note 1). The reaction is extremely rapid either with the protein or with water. The reagent is relatively insoluble in water; it is therefore necessary to first dissolve it in an organic solvent (e.g., dioxane) and then to add it to the protein solution in buffer. Unlike that of most other modifying reagents, the final organic solvent concentration in the reaction mixture is relatively high (5-15%). Determination of the number of modified tryptophans is done spectrophotometrically.

Keywords

Sodium Hydroxide Lysine Residue Marked Selectivity Protein Solution Tryptophan Residue 
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.

References

  1. 1.
    Horton, H. R. and Koshland, D. E., Jr. (1972) Modification of proteins with active benzyl halides. Meth. Enzymol. 25, 468–482.CrossRefGoogle Scholar

Copyright information

© Humana Press Inc., Totowa, NJ 2002

Authors and Affiliations

  • Dan S. Tawfik
    • 1
  1. 1.Department of Biological Chemistrythe Weizman Institute of ScienceRehovotIsrael

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