Development and application of highly sensitive labeling reagents for amino acids

Simultaneous separation and identification of all structural isomers and enantiomers of aminobutyric acid using a highly sensitive chiral resolution labeling reagent

“…We previously developed several chiral resolution labeling reagents with a highly sensitive tag. [16][17][18] Via labeling with our labeling reagents, we have succeeded in highly sensitive separation and identication of substances that are difficult to separate using conventional chiral resolution labeling reagents. [19][20][21] Herein, we propose a highly sensitive analytical method for the simultaneous separation and identication of all aminobutyric acids using LC-MS under simple analytical conditions aer labeling with a highly sensitive chiral resolution labeling reagent, 1-uoro-2,4-dinitrophenyl-5-L-valine-N,Ndimethylethylenediamine amide (L-FDVDA, Fig.…”

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

“…17 Additionally, the samples labeled with D-FDLDA exhibited better resolution and MS sensitivity than those labeled with conventional chiral resolution labeling reagents. [17][18][19] In our study, we identified the racemised and isomerised Asp residues in Aβ fragments (chemical structures of racemised and isomerised Aβ 1-3 fragments, Fig. 1b) digested with trypsin and endoproteinase Glu-C by LC-MS using D-FDLDA (Fig.…”

“…D-FDLDA binds to the N-terminal amino group of the peptides and the amino group of the lysine (Lys) side chain. [17][18][19] Aβ 1-3 and Aβ 6-11 bind to one labeling reagent via the N-terminal amino group, and Aβ 23-28 binds to two labeling reagents via the N-terminal amino group and C-terminal Lys side chain. The ee of the labeling reagent must be >99.9% for the precise identification of racemisation and isomerisation of Asp residues in Aβ fragments.…”

“…4b). The Aβ [17][18][19][20][21][22][23][24][25][26][27][28] fragments used in previous studies exhibited significantly higher fluorescence intensity (Fig. 4b).…”

“…17 Additionally, the samples labeled with d -FDLDA exhibited better resolution and MS sensitivity than those labeled with conventional chiral resolution labeling reagents. 17–19…”