New insights into the bonding arrangements of l- and d-glutamates from solid state 17O NMR

Magic angle spinning (MAS) from l- and d-glutamic acid–HCl at 14.1 T produces highly structured and very similar NMR spectra. Lines from all 4 oxygen sites are readily distinguished and assigned. These 17O NMR spectra are very different from the previously reported 17O spectrum of the d,l-form presumably because that was a racemic crystal. 17O NMR from l-monosodium glutamate–HCl is very different again requiring the application of double angle rotation and 3 quantum MAS NMR to provide resolution of 5 different sites. Hence high resolution 17O solid state NMR techniques offer possible new insight into biochemical bonding processes.