Liquid secondary ion mass spectra of 2-iminothiolane derivatives.
The derivatization reaction of 2-iminothiolane with several small peptides has been studied using liquid secondary ion mass spectrometry. The 2-iminothiolane reagent reacts with side-chain amino groups and with N-terminal amines in peptides. Addition of 2-iminothiolane introduces a free sulfhydryl group and an immonium group into the peptide. The signal intensity for the derivative of a small peptide is approximately the same as that of the [M + H]+ ion of the same underivatized peptide from a glycerol solution. The pattern of dissociation observed in the product ion MS/MS spectrum is altered to reflect the derivative. The sulfhydryl group introduced via 2-iminothiolane reaction further allows for the incorporation of maleimide fluorophores into the peptide for sensitive detection by ultraviolet/visible absorption or fluorescence. This work also reports a previously unrecognized recyclization side-reaction that involves loss of the immonium group during the derivatization reaction.
School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta 30332-0400.
M G
MG
Bartlett
K L
KL
Busch
D000595:Amino Acid Sequence; D003432:Cross-Linking Reagents / Q000737:chemistry*; D004744:Enkephalin, Methionine / Q000737:chemistry; D005456:Fluorescent Dyes; D007096:Imidoesters / Q000737:chemistry*; D008301:Maleimides / Q000737:chemistry; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013438:Sulfhydryl Compounds / Q000737:chemistry
D003432:Cross-Linking Reagents; D005456:Fluorescent Dyes; D007096:Imidoesters; D008301:Maleimides; D013438:Sulfhydryl Compounds; D004744:Enkephalin, Methionine; C005905:methyl 4-mercaptobutyrimidate