TITLE: Computer simulations of micromanipulation of proteins and DNA

SPEAKER: Professor Jeff Z. Y. Chen,

TIME: Thursday Jan. 23, 2002 at 3 PM

PLACE: George P. Williams, Jr. Lecture Hall, (Olin 101)

In this talk, I will discuss how to create computationally tractable models that can be used to understand the physical properties observed in mechanical manipulation of proteins and DNA. As the first example, a protein molecule under the stress of an external denaturing force acting on a terminal end or on the entire molecule is expected to unfold, possibly through a few intermediate stages. We have investigated two protein models under various types of denaturing force fields using the collision molecular-dynamics simulation, in order to critically examine the relationship between the folding pathways observed in different protein denaturing experiments. As the second example, a double stranded DNA molecule pulled with a force acting on the strand terminals exhibits a partially denatured structure or can be completely unzipped when the pulling force goes beyond a critical force. Through computer simulation, we have evaluated the critical force and demonstrated the universal scaling behavior of the extension-force curve based on studies of various disorder sequences.