4896-76-8

Upstream product

• 1268451-59-7 C₅H₈⁽²⁾HNO₂ 
• 56-40-6 glycine 

Downstream Products

• 4896-77-9 glycine-d5 

Relevant academic research and scientific papers

Deuteron Chemical Shift and EFG Tensors in α-Glycine

By computer fitting of resonance lines in deuteron spectra of perdeuterated crystals, deuteron chemical shifts in crystals are measured with an accuracy of +/- 0.3 ppm.Second-order quadrupole shifts must be taken into account.An important advantage of the method is that the measured chemical shifts and the shift tensors are automatically related to EFG tensors which can be assigned easily.The method is applied to α-glycine for which a shift anisotropy Δ? = 21 +/- 9 ppm has been reported for the methylene protons.Full EFG and chemical-shift tensors are reported at both methylene deuteron sites, and motionally averaged tensors are reported for the ND3+ sites.The shift anisotropies Δ? for the methylene deuterons are 4.7 and 9.4 ppm, respectively.Significant differences of the isotropic shifts and quadrupole coupling constants are also observed for these two deuterons.They are interpreted as evidence for the formation of a weak C-H...O hydrogen bond in α-glycine.

Substituent effects on electrophilic catalysis by the carbonyl group: Anatomy of the rate acceleration for PLP-catalyzed deprotonation of glycine

First-order rate constants, determined by 1H NMR, are reported for deuterium exchange between solvent D2O and the α-amino carbon of glycine in the presence of increasing concentrations of carbonyl compounds (acetone, benzaldehyde, and salicylaldehyde) and at different pD and buffer concentrations. These rate data were combined with 1H NMR data that define the position of the equilibrium for formation of imines/iminium ions from addition of glycine to the respective carbonyl compounds, to give second-order rate constants kDO for deprotonation of α-imino carbon by DO-. The assumption that these second-order rate constants lie on linear structure-reactivity correlations between log kOL and pKa was made in estimating the following pKa's for deprotonation of α-imino carbon: pKa = 22, glycine-acetone iminium ion; pKa = 27, glycine-benzaldehyde imine; pKa ≈ 23, glycine-benzaldehyde iminium ion; and, pKa = 25, glycine-salicylaldehyde iminium ion. The much lower pKa of 17 [Toth, K.; Richard, J. P.J. Am. Chem. Soc. 2007, 129, 3013 -3021 ] for carbon deprotonation of the adduct between 5′-deoxypyridoxal (DPL) and glycine shows that the strongly electron-withdrawing pyridinium ion is unique in driving the extended delocalization of negative charge from the α-iminium to the α-pyridinium carbon. This favors carbanion protonation at the α-pyridinium carbon, and catalysis of the 1,3-aza-allylic isomerization reaction that is a step in enzyme-catalyzed transamination reactions. An analysis of the effect of incremental changes in structure on the activity of benzaldehyde in catalysis of deprotonation of glycine shows the carbonyl group electrophile, the 2-O- ring substituent and the cation pyridinium nitrogen of DPL each make a significant contribution to the catalytic activity of this cofactor analogue. The extraordinary activity of DPL in catalysis of deprotonation of α-amino carbon results from the summation of these three smaller effects.