1P-11 PDF
Quantification of amino acids in biological samples by dabsylation isotope labeling
Amino acids are important metabolites for various biological systems. Proteinogenic amino acids are only a part of biologically important amino acids. For example, in animals, free D-amino acids play important roles in the central nervous system, secretary organs, and osmotic control. Marine bioactive peptides contain various kinds of unusual amino acids such as methylated amino acids. Post-translational modification of proteins produces many kinds of amino acid derivatives. Therefore, accurate measurement of amino acids is required in many research fields. However, methods used at present have respective strength and weakness for their molecular species coverage and dynamic range. To measure amino acids in small biological samples, we have been developing a method using stable isotope tags and a conventional ion-trap mass spectrometer with a moderate mass resolution. We synthesized 13C6-dabsyl chloride (DabsCl, 4-dimethylaminoazobenzene-4’-sulfonyl chloride). By using 12C- and 13C6-DabsCl, we can discriminate amino acids contained in a target sample and those in a control sample in a single chromatography run. In the present study, we evaluated the reliability of our method by measuring amino acids in standard mixtures and biological samples including land snail (Achatina fulica) hemolymph. The amino acid profile of the hemolymph was successfully obtained.