N super( alpha ) Selective Acetylation of Peptides

• Published in: Mass spectrometry (Tokyo, Japan) Vol. 1; no. 2; p. A0010
• Main Authors: Mikami, Toshiyuki, Takao, Toshifumi, Yanagi, Kazunori, Nakazawa, Hiroshi
• Format: Journal Article
• Language: English
• Published: 01.01.2013
• Subjects: Acetylation; Anhydrides; Blocking; Deuteration; Lysine; Peptides; Quantitative analysis; Running
• ISSN: 2187-137X; 2186-5116
• DOI: 10.5702/massspectrometry.A0010

A chemical tag at the peptide N-terminus, in combination with MS, can be useful for quantitative analysis, N-terminal peptide identification, or peptide sequencing. Here we report on the N super( alpha ) selective acetylation of a peptide using acetic anhydride, a popular reagent for the modification of amino groups, without the need for the blocking of lysine side-chain epsilon -amino groups, which is usually required for N super( alpha ) selective acetylation. By controlling the amount of acetic anhydride used and running the reaction at 0 degree C, it is possible to preferentially acetylate the alpha -amino group. As a typical application of the method, a tryptic digest of an N-terminally blocked protein, cytochrome c, was directly acetylated using the present method. When deuterated acetic anhydride was used as the reagent, the N-terminal blocked peptide could be easily identified as a non-labeled ion peak while the N super( alpha )-acetyl groups of all the other peptides were deuterated.