2P-09 PDF
A selective analytical method for racemized peptides by chiral-derivatization
We have found the biologically uncommon isomerized aspartic acid residues and calculated their isomerization ratio in peptides and proteins by a combination of the chiral derivatization with LC-MS/MS based proteomics. Cationic derivatization reagents, DBD-Py-NCS and DBD-Apy were derivatized to the amino groups and carboxyl groups in the peptides, respectively. The tryptic peptide (FVIFLDVK) in αA-Crystallin which contained an isomerized Asp residue was used as the model peptide. The derivatized peptide isomers were completely separated by this method. These results show that this proposed chiral peptide LC-MS/MS method using chiral derivatization provides a rapid and sensitive analysis for post translational Asp isomerization sites in aging proteins.