Bubbles and Mismatches in DNA Melting : Bubbles and Mismatches in DNA Melting

ISBN-13: 9783639070170 / Angielski / Miękka / 2009 / 84 str.

Yan Zeng

Opis

We obtained the first experimental measurements ofthe length of thedenaturation bubble appearing in the DNA meltingtransition. This isachieved by working with short oligomers which canform only one bubbleper molecule. Using a quenching technique to trap thebubble states, wecould measure the length of the bubble and therelative weights of thebubble states as a function of temperature. We foundthat the averagebubble size grows for increasing temperature, butreaches a plateau at alength of order B (the length of the AT region).After the plateau, theaverage bubble length jumps to 1. This jump of theorder parameter is asignature of a discontinuous transition, one wherethe bubble size remainsfinite up to critical temperature of strandseparation. For abubble flanked by double-stranded regions, thenucleation size is around 3bases. For bubbles opening at the ends of themolecule there is nonucleation threshold. For the first time we showexperimentally that asingle mismatch transforms a transition with manyintermediates into anearly two-state transition for oligomer length inthe range of 20 to 40bases.

O autorze

Dr. Yan Zeng is Assistant Professor of Physics at Savannah State
University. She earned her B.S.(Electronics) from Peking
University, M.S.(Physical Electronics) from Peking University,
and Ph.D. (Physics) from University of California at Los
Angeles. Now she is working on Biophysics experiments and
Physics Education.