Biopolymers and cell. 1998; 14 (5): 419 - 427

How structural changeability of nitrogen bases affects macroscopic properties of their crystals

D. M. Hovorun

The author stands up for the idea accordingly to which uncommon optical and physical properties of nitrogen bases ( unregularity of their anhydrous lattices which becomes essentially reduced under moistening and deuteration, temperature anomalies of dielectric permeability and tangent of loss angle, availability of defects — traps of charge carriers, violations of selection rules in polarized vibrational spectra etc.) are determined by stereochemical non-rigidity of the bases themselves. The nitrogen bases crystals with amino group and their hydrates are essentially John-Teller crystals with all the ensuing consequences. Such approach enables the author to explain macrostructural origing of the propeller configuration of the layer package of nitrogen bases with amino group in crystal slate by the increase of their inversion energy up to the values several times exceeding kT, under transition from the free state to the crystal one which is the result of the p-n-conjugation disturbance and specific electrostatic contacts of lone pair of amino nitrogen atom with positively charged hydrogen and carbon atoms from upper and lower molecular layers. Similar reason is based on the propeller configuration of Watson-Crick pairs in DNA and its wedge-like relative orientation. The evaluations of amino group inversion energies of nucleotide bases for crystals and in DNA were done.