Improved Chiral Separations for Enantiopure D- and L-Amino Acids
The Application Notebook
Several D-amino acids have been found to be important in brain neurochemistry and changes in the levels of these amino acids coincide with development of different diseases. For example, the D-form of serine is involved in modulation of the NMDA receptor and has been implicated in a broad spectrum of disorders including schizophrenia, ischemia, and epilepsy.
D-amino acids have historically been considered unnatural since naturally produced proteins are composed exclusively of L-amino acids. While bacterial cell walls were known to contain D-amino acids, their presence in humans and higher organisms has been reported more recently.
Crown-ether chiral stationary phases (CSPs) have been found to be especially well suited for separation of D- and L-amino acid enantiomers. Regis Technologies' crown-ether CSP ChiroSil® is a trifunctionally bonded (18-crown-6)-2,3,11,12-tetracarboxylic CSP available in both (+) and (-) conformations which thereby enables inversion of the elution order of the D- and L- isomers.
Figure 1: HPLC analytical screen of Serine. Column: ChiroSil® SCA(-), 15 cm à 4.6 mm, 5 µm. Mobile Phase: 84% MeOH/16%H2O, 5 mM HClO4. k'1: 1.37 α: 1.99
In this application note, we present separation of the D- and L-isomers of two neurophysiologically relevant amino acids, serine and glutamic acid, by high pressure liquid chromatography (HPLC) using the CSP.
Figure 2: HPLC analytical screen of glutamic acid. Column: ChiroSil® SCA(-), 15 cm à 4.6 mm, 5 µm. Mobile phase: 84% MeOH/16%H2O, 5 mM HClO4. k'1: 1.45 α: 1.60.
Experimental Conditions
Compounds were separated on ChiroSil® SCA(-) chiral columns using standard dimensions, 15 cm à 4.6 mm i.d. packed with 5 micron particles. ChiroSil® is a registered trademark of RStech Corporation of Daejeon, South Korea.
Conclusions
Baseline enantiomeric resolution of serine and glutamic acid amino acids was achieved in less than 10 min using the crown-ether CSP method described here. The ChiroSil® CSP is a beneficial column in analyzing amino acids in the neurochemistry field.
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The 26th Norwegian Symposium on Chromatography
March 29th 2024The 26th Norwegian Symposium on Chromatography was held 21–23 January 2024. The symposium has strong traditions in the Norwegian separation science community, serving as a forum for excellent scientific talks, networking, and social events.
