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Peptide Sequencing: Edman Degradation definitions

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  • Edman Degradation
    A chemical method for sequencing peptides from the N-terminus by sequentially removing and identifying amino acids.
  • Phenylisothiocyanate
    A reagent abbreviated as PITC, used to react with the N-terminal amino group during peptide sequencing.
  • N-Terminus
    The free amino end of a peptide chain where sequencing begins in Edman degradation.
  • Thiourea Derivative
    An intermediate formed when the N-terminal amino group reacts with PITC during the first step of Edman degradation.
  • Thiazolinone Derivative
    A cyclic intermediate produced after cyclization and cleavage, prior to rearrangement in Edman degradation.
  • Phenylthiohydantoin
    A stable product formed after rearrangement, used to identify the cleaved amino acid chromatographically.
  • Nucleophilic Addition
    A reaction step where the amino group attacks the carbon of PITC, initiating peptide sequencing.
  • Nucleophilic Acyl Substitution
    A mechanism involved in cyclization, where a nucleophile replaces a leaving group on a carbonyl carbon.
  • Proton Transfer
    A process where a hydrogen ion shifts between atoms, stabilizing intermediates during peptide sequencing.
  • Acidic Hydrolysis
    A reaction using acid to break bonds, facilitating ring opening and rearrangement in Edman degradation.
  • Chromatographic Characterization
    A technique used to identify the phenylthiohydantoin derivative and thus the cleaved amino acid.
  • Peptide Chain
    A sequence of amino acids linked by peptide bonds, subject to sequential cleavage in Edman degradation.
  • Leaving Group
    An atom or group that departs with electron pairs during substitution or elimination steps in the reaction.
  • Tautomerization
    A rearrangement involving the shift of a hydrogen and a double bond, converting enol-like intermediates to keto forms.
  • Ring Closure
    A step where a linear intermediate forms a cyclic structure, finalizing the rearrangement in Edman degradation.