Synthesis of D-labeled naphthyliodoacetamide and application to quantitative peptide analysis by isotope differential mass spectrometry

D-labeled and -unlabeled N-β-naphthyliodoacetamides have been synthesized for specific modification of the sulfhydryl groups of cysteine residues in proteins or peptides, and have been applied to quantitative analysis of several peptides. A combination of these reagents, coupled with mass spectrometry, is anticipated to serve as a useful tool for quantitative analysis of peptides and hence proteins.