The Hampering Effect of Heavy Water (D₂O) on Oscillatory Peptidization of Selected Proteinogenic α-Amino Acids

We present an overview of our studies on the hampering effect of heavy water (D₂O) on spontaneous oscillatory peptidization of selected proteinogenic α-amino acids. The investigated set of compounds included three endogenous and two exogenous species. The experiments were carried out with use of high-performance liquid chromatography (HPLC), mass spectrometry (MS) and scanning electron microscopy (SEM). These techniques were chosen to demonstrate spontaneous oscillatory peptidization of α-amino acids in an absence of D₂O (HPLC) and the hampering effect of D₂O on peptidization (HPLC, MS and SEM). The HPLC analyses were carried out at 21 ± 0.5°C with each α-amino acid freshly dissolved in the binary liquid mixture of organic solvent + H₂O, 70:30 (v/v) or in pure D₂O for several dozen hours or several hours, respectively. The analyses with use of MS and SEM were carried out, respectively, after 7 days and 1 month of sample storage period in the darkness at 21 ± 0.5°C and for these experiments, each α-amino acid was dissolved in the liquid mixture of organic solvent + X, 70:30 (v/v), where X: H₂O + D₂O in volume proportions from 30:0 to 0:30. The results obtained with use of HPLC, MS and SEM point out to the strong hampering effect of D₂O on the oscillations and peptidization yields, yet the dynamics of these processes significantly depends on chemical structure of a given α-amino acid.