Electronic structure of biopolymers and possible mechanisms of chemical carcinogenesis

Abstract

As an illustration of the applicability of the coherent potential approximation (CPA) method to the treatment of aperiodic biopolymers (DNA and proteins) the results of a calculation with a k-dependent self-energy are presented in the case of the (SN), and (SN-H), mixed system. Further we givc ah initio SCF LCAO band structures for polyglycine, which were corrected with the aid of the electron polaron model for long-range correlation and with the help of the 080 method for excitonic effects. Finally. on the basis of the electronic structure of DNA and proteins, difrerent possible mechanisms of chemical carcinogenesis are described.

Free radicals produced in the interaction of cysteine with carbonyls of biological relevance

“…These calculations verify the basic tenets of the intramolecular charge-transport theory, indicating that short-range, rather than long-range, electron transport within proteins is feasible [3], and that weak charge transfer between amines and carbonyls does indeed occur Experimentally the model charge acceptor methylglyoxal (2, oxopropanal) reacts with proteins to form colored products [ 6 ] with an increased electrical conductivity [7] and a small free radical content [8]. Amine models have been investigated in the hope that their fast tumbling in solution might permit electron spin resonance hyperfine couplings to be obtained together with corresponding structural information [9].…”

A nonempirical model potential technique for calculations of band structures of polymers

“…(c) The additive character of the potential makes the procedure well adapted for a study of structurally disordered polymers and of copolymers and thus well designed to complement recently proposed techniques [26].…”

Perturbation of cell-selfregulation through oncoproteins

“…In a previous article [7] we have reviewed the most probable local as well as longrange effects caused by carcinogen binding to DNA andtor proteins. In a subsequent publication [8] the role of conformational solitons caused by the release of bulky carcinogens bound to a nucleotide base stack (the carcinogen binding distorts the conformation of the double helix and therefore also changes the interaction between the electrons belonging to the stacked bases) is discussed in detail as one of the most probable forms of the long-range effects of carcinogns via which they can influence DNA-protein interactions in a nucleoprotein.…”