Separation of amyloid β fragment peptides with racemised and isomerised aspartic acid residues using an original chiral resolution labeling reagent

We developed a system to separate and identify racemised and isomerised aspartic acid (Asp) residues in amyloid beta (A beta) by labeling with an original chiral resolution labeling reagent, 1-fluoro-2,4-dinitrophenyl-5-d-leucine-N,N-dimethylethylenediamine-amide (d-FDLDA). The racemised and isomerised Asp residues labeled with d-FDLDA in A beta fragments generated by digesting with trypsin and endoproteinase Glu-C were separated and identified by liquid chromatography-mass spectrometry (LC-MS) under simple gradient conditions. Furthermore, the labeled A beta fragments did not aggregate and remained stable at least for 1 week at 4 degrees C.

Automated summary

We developed a system to separate and identify racemised and isomerised Asp residues in A beta using a chiral resolution labeling reagent, d-FDLDA. The labeled residues were separated and identified using LC-MS under simple gradient conditions. The labeled A beta fragments remained stable and did not aggregate for at least 1 week at 4 degrees C.