Alignment-caused Insulator to Semiconductor Transition in Solid-phase DNA Duplexes and its Possible Biological Function.
Upon parallel alignment of their main axes packed ensembles of DNA duplexes undergo an insulator to one dimensional donor-doped semiconductor transition. (Hartwich, Caruana, de-Lumley-Woodyear, Wu, Campbell and Heller JACS, 1999, 121, 769). Wolf, Frenkel, Arad, Finkel, Kolter and Minsky (Nature 1999, 476, 71) reported stress induced crystallization of DNA in E. Coli. The proposed biological function of the stress-induced alignment, leading to insulator semiconductor transition, is to stabilize genetically essential regions of the duplexes against oxidative and reductive damage. In semiconductors, but not in insulators, holes injected by oxidizing radicals, as well as electrons injected by reducing radicals, diffuse to and will react in remote sacrificial traps. The reaction sites are probably located at the interface between the aligned semiconducting and the non-aligned insulating domains, which resemble in their behavior silicon or III-V semiconductor crystallite surfaces. In the case of reactions of oxidizing radicals, such as OH, peripheral G bases in pendant single strands or in nonaligned domains are the most likely sacrificial bases. It is conceivable that nature's strategy in preserving the fidelity of genetic information is to trap the diffusing hole or electron at a site that is genetically non-essential.
Deparment of Chemical Engineering and Texas Materials Institute,