Alkan Kabakcioglu, Koc University, DNA folding thermo/dynamics with a twist
Date: Mon. September 24th, 2018, 12:45 pm-1:45 pmDNA folding thermo/dynamics with a twist
Alkan Kabakcioglu, Koc University, Istanbul
DNA denaturation is possibly one of the earliest problems in biophysics that grabbed the attention of statistical physicists. The nature of the folding/melting transition has been subject to debate since 60’s until a breakthrough in the past decade mostly settled the question. We recently readdressed the problem for circular DNA (which has a topologically imposed, fixed linking number due to helicity) and found that the melting behavior is qualitatively different from that of the unconstrained DNA with freely dangling ends. In particular we argue, by generalizing the predominant theoretical model in this field, that the transition rigorously follows an “inverted” BEC scenario where a macroscopic loop appears at Tc and grows steadily with increasing temperature.
Helicity is also relevant in hybridization dynamics. We very recently showed, by molecular dynamics simulations, that DNA/RNA hairpin folding times scale with the molecule length N as N^(1+v), where v=3/(d+2) is the Flory exponent, only when the structure is helical. We propose an alternative scaling behavior in absence of helicity, as well as a phenomenological picture for our observations.
Host: Michael Hinczewski