Seite - 9 - in Charge Transport in DNA - Insights from Simulations

biological relevance of such molecular systems, the recent interest in the electric properties ofmicrohydratedDNAbringsonanatural question–what is its struc- ture? The only studies on aDNAspecies in a clusterwithwatermoleculeswere performed byMazur, who concentrated on another aspect though. A dsDNA in a quite large cluster of several thousandwatermoleculeswas simulated to show that the structure deviates little from the experimental one as well as from that observed in a simulation under periodic boundary conditions with a necessarily larger number ofwatermolecules.[48]Also, reversible B–Aconformational transi- tionswere observed, dependingof the (varied) amount ofwater in the cluster.[49] Thisamountwasprobablystill too largecomparedwith thatboundtoDNAin the single-molecule conductivity experiments. However, the considerable experimental and theoretical research interest makes double-strandedDNAan archetypical system to study the dependence of CT ef- ficiency on themolecular environment, especially thedegree of hydration. There- fore, thefirst aimof thiswork is todescribe the structure andmechanical stability of several short double-strandedDNAoligomers. Later on, the hole transport in double-strandedDNAoligonucleotides is studied in aqueous solution aswell as undermicrohydration conditions. Possible consequences forCT ingeneralwill be discussed. 9 Introduction