Microanalysis of D/L-amino acid residues in peptides and proteins

authors of this article describe the determination of D/L-amino acid residu es in peptides and proteins at microgram levels. They fluorescently tagged amino acid residues with naphthalene-2,3-dicarboxaldehyde and performed ena ntioseparation using beta -cyclodextrin-modified micellar electrokinetic ch romatography in the presence of methanol as an organic modifier. Their sepa ration was coupled with laser-induced fluorescence detection for sensitive determination. The authors determined configurations of amino acid residues in peptides with 10 mug of hydrolyzed peptide material. They demonstrated the assessment of enantiomeric purity for synthetic peptides by their propo sed method. They also applied the method to determining D-aspartic acid, fr ee and bound in proteins in rat brains. Although they detected high levels of free D-aspartic acid, no D-aspartic acid was bound in proteins.