High-sensitivity isoelectric focusing of biotinylated peptides: A new method

Lothar Seik, Annette Beck, Claude P. Muller*

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review


A novel technique to selectively analyze prelabeled peptides by isoelectric focusing (IEF) is presented. The conditions are described for biotinylation of peptides, their separation in polyacrylamide gels by IEF, and their fixation to the gel matrix with glutaraldehyde. The gels are developed by a color reaction catalyzed by an avidin-coupled enzyme. The technique is suitable for peptides with at least one free amino group of guanidino group after N-terminal biotinylation. The presence of other peptides or proteins does not interfere with the detection. The sensitivity is below 10 pmol, representing a 1000-fold improvement over existing techniques for analyzing low molecular weight peptides by IEF.

Original languageEnglish
Pages (from-to)96-103
Number of pages8
JournalAnalytical Biochemistry
Issue number1
Publication statusPublished - 15 May 1988
Externally publishedYes


  • angiotensin II
  • avidin-enzyme staining
  • biotinylation
  • isoelectric focusing
  • peptide
  • polyacrylamide gel


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