Stereoselective Amine-omics Using Heavy Atom Isotope Labeled l‑ and d‑Marfey’s Reagents

Biological amines and amino acids play essential roles
in many
biochemical processes. The chemical complexity of biological samples
is challenging, and the selective identification and quantification
of amines and amino acid stereoisomers would be very useful for amine-focused
“amino-omics” studies. Many amines and amino acids are
chiral, and their stereoisomers cannot be resolved on achiral media
without chiral derivatization. In prior studies, we demonstrated the
use of Marfey’s reagenta chiral derivatization reagent
for amines and phenolic OH groupsfor the LC–MS/MS resolution
and quantification of amines and amino acid stereoisomers. In this
study, a heavy atom isotope labeled Marfey’s reagent approach
for the stereoselective detection and quantification of amines and
amino acids was developed. Heavy (13C2) l-Marfey’s (Hl-Mar) and heavy (2H3) d-Marfey’s (Hd-Mar) were synthesized
from 13C2-l-Ala and 2H3-d-Ala, respectively. Both light and heavy Marfey’s
reagents were used to derivatize standard amine mixtures, which were
analyzed by LC–QToF-HRMS. Aligned peak lists were comparatively
analyzed by light vs heavy Mar mass differences to identify mono-,
di-, and tri-Marfey’s adducts and then by the retention time
difference between l- and d-Mar derivatives to identify
stereoisomers. This approach was then applied to identify achiral
and chiral amine and amino acid components in a methicillin-resistant Staphylococcus aureus (MRSA) extract. This approach shows
high analytical selectivity and reproducibility.