Michigan Technological University

Department of Physics

is pleased to announce a colloquium

with

Yang Zhang, Ph.D.
 Laboratory of Computational Genomics,
 Donald Danforth Plant Science Center

Elasticity of Individual Poly-nucleotide Molecule


The elastic property of deoxyribonucleic acids (DNA) is essential to their functions in living cells. Therefore understanding function of DNA molecules requires an understanding of their elasticity. I will discuss the recent experimental observations of elastic response of both single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) molecules under externally applied force fields. To understand these experimental observations, we model the dsDNA molecules as two interwound wormlike chains bound by dominant hydrogen bonds. The structural deformation of dsDNA is charactered by a new-introduced folding angle of suger-phosphate strand and the molecule center axis. The ssDNA, in our calculation, is modeled as a freely jointed chain with elastic bonds, with electrostatic, base-pairing and stacking interactions incorporated. The path integral method and Monte Carlo technique are used to calculate the thermodynamics of pulling the single poly-nucleotide molecules. The comprehensive agreements are found between the theoretical calculations and experimental measurements of stretching the torsionally relaxed and supercoiled dsDNA, and of pulling ssDNA with random and designed poly(dA-dT)/(dG-dC) nucleotide sequences.

January 24, 2002, Thursday

Fisher Hall, Room 139

Refreshments will be served.