Identification of Phosphorylation Sites in Peptides Using a Microsequencer

Peter T. Roach, Yuhuan Wang

Research output: Contribution to journalArticle

15 Scopus citations


This chapter discusses the identification of phosphorylation sites in peptides using a microsequencer. As examples of protein phosphorylation proliferate, identifying the specific phosphorylated residues in peptides becomes a more frequent task. Analysis of phosphorylation sites has not kept pace with advances in amino acid sequencing in large part because the standard Edman degradation procedures do not yield stable phenylthiohydantoin (PTH) derivatives of phosphoserine or phosphothreonine residues; the derivatives of Edman degradation breaking down during the acid cleavage step to release inorganic phosphate. Quantitation of the amount of free inorganic phosphate measures the cumulative release of phosphate from phosphoserine or phosphothreonine residues up to the interrupt cycle and can be used to judge which residues were phosphorylated. The equipment required includes a pair of scissors, gas-phase or pulsed liquid-phase microsequencer, and a means for separating and quantitating phosphate and phosphopeptide.

Original languageEnglish (US)
Pages (from-to)200-206
Number of pages7
JournalMethods in Enzymology
Issue numberC
StatePublished - Jan 1991
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology

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