Determination of N‐terminal myristoylation of proteins using a combined gas chromatographic/mass spectrometric assay of derived myristoylglycine: Electron impact‐induced fragmentation of acylglycine derivatives
1995
A method based on gas chromatography/mass spectrometry is described for the detection of N‐terminal myristoylation of proteins. Myristoylglycine, derivatized as its trimethylsily (TMS) ester, gave an electron impact mass spectrum containing abundant molecular and and [M CH₃]⁺ ions, together with several ions diagnostic of the acyl glycine moiety, namely at m/z 145, 158, 172 and 189. The compositions of these ions and the mechanisms that produced them were investigated by high‐resolution mass measurements, deuterium labelling and the preparation of analogous compounds. As these were present in the spectra of all acylglycines examined, they could be used as markers for these compounds. A selected‐ion monitoring method for the detection of myristoylglycine was set up using the above ions and was used to confirm the presence of N‐terminal myristoylation in three reference peptides. A series of ions produced by radical‐induced cleavage of the alkyl chain following TMS group migration and elimination of carbon dioxide gave information on the structure of the chain and could be used to determine the structure of other potential acylglycines such as those with unsaturated acyl chains. Thus the derivatives could be used not only to detect myristoylation of protein, but also to detect and determine the structures of other acyl substituents.
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