Modification of N-terminal α-amino groups of peptides and proteins using ketenes

Anna On Yee Chan, Chi Ming Ho, Hiu Chi Chong, Yun Chung Leung, Jie Sheng Huang, Man Kin Wong, Chi Ming Che

Research output: Journal article publicationJournal articleAcademic researchpeer-review

116 Citations (Scopus)


A method of highly selective N-terminal modification of proteins as well as peptides by an isolated ketene was developed. Modification of a library of unprotected peptides XSKFR (X varies over 20 natural amino acids) by an alkyne-functionalized ketene (1) at room temperature at pH 6.3 resulted in excellent N-terminal selectivity (modified α-amino group/modified ε-amino group = >99:1) for 13 out of the 20 peptides and moderate-to-high N-terminal selectivity (4:1 to 48:1) for 6 of the 7 remaining peptides. Using an alkyne-functionalized N-hydroxysuccinimide (NHS) ester (2) instead of 1, the modification of peptides XSKFR gave internal lysine-modified peptides for 5 out of the 20 peptides and moderate-to-low N-terminal selectivity (5:1 to 1:4) for 13 out of the 20 peptides. Proteins including insulin, lysozyme, RNaseA, and a therapeutic protein BCArg were selectively N-terminally modified at room temperature using ketene 1, in contrast to the formation of significant or major amounts of di-, tri-, or tetra-modified proteins in the modification by NHS ester 2. The 1-modified proteins were further functionalized by a dansyl azide compound through click chemistry without the need for prior treatment.
Original languageEnglish
Pages (from-to)2589-2598
Number of pages10
JournalJournal of the American Chemical Society
Issue number5
Publication statusPublished - 8 Feb 2012

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry


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