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Updated: Jun 8, 2026

Metabolic Pathway Confirmation and Discovery Through 13C-labeling of Proteinogenic Amino Acids
Published on: January 26, 2012
N-Terminal sequencing by mass spectrometry through specific fluorescamine labeling of α-amino groups before tryptic
Neeraj Dhaunta1, Uzma Fatima, Purnananda Guptasarma
1Protein Science & Engineering, Institute of Microbial Technology, Sector 39-A, Chandigarh 160 036, India.
Abstract:
We present a single-step procedure for the specific mass labeling of unblocked protein N termini. We show that the dye fluorescamine, which is commonly assumed to require mildly alkaline conditions for undergoing a nonspecific reaction with α- and ε-amino groups associated with amino acids, in fact shows a specific reaction only with α-amino groups present at protein N termini when mildly acidic conditions are used. We use this finding to label, identify, and sequence the trypsinolysis-derived N-terminal peptide of lysozyme, using only mass spectrometry, to illustrate how this method could be used with other proteins.
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