Determination of the effective charge of a protein in solution by capillary electrophoresis

Jinming Gao, Frank A. Gomez, Ralph Härter, George M. Whitesides

Research output: Contribution to journalArticle

63 Citations (Scopus)

Abstract

This paper describes two methods to estimate the effective charge of a protein in solution by capillary electrophoresis and demonstrates these methods by using representative proteins. In one method, a 'charge ladder'-a series of derivatives of a protein differing by known increments of charge but differing only minimally in hydrodynamic drag-is generated by covalent modification of the ε-amino groups of lysines with 4-sulfophenyl isothiocyanate or acetic anhydride. In the second method, the equivalent of a charge ladder is produced by noncovalent association of a protein with differently charged ligands. Analysis of the electrophoretic mobilities of the protein and its derivatives as a function of added charge allows the effective charge to be estimated for the unmodified protein. This type of analysis permits estimation of the effective charge of a protein without knowing its composition, structure, or amino acid sequence.

Original languageEnglish (US)
Pages (from-to)12027-12030
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Volume91
Issue number25
DOIs
StatePublished - Dec 6 1994

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Capillary Electrophoresis
Proteins
Hydrodynamics
Lysine
Amino Acid Sequence
Ligands

Keywords

  • protein charge ladders

ASJC Scopus subject areas

  • Genetics
  • General

Cite this

Determination of the effective charge of a protein in solution by capillary electrophoresis. / Gao, Jinming; Gomez, Frank A.; Härter, Ralph; Whitesides, George M.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 91, No. 25, 06.12.1994, p. 12027-12030.

Research output: Contribution to journalArticle

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