Thursday, Mar. 11, 11:00-12:00

A helicase protein moves along a double-stranded nucleic acid molecule and unwinds the double helix.  This talk presents a model for the coupling

 between helicase translocation and duplex unwinding.  Two different cases -- active and passive opening -- are usually distinguished.  In active

opening, the helicase directly destabilizes the double-stranded nucleic acid (dsNA) to promote opening.  Passive opening implies that the helicase

binds ssNA available when a thermal fluctuation partially opens the dsNA.  We formulate a discrete model for helicase motion.  An interaction potential

describes how the helicase may accelerate duplex unwinding when near a junction between single-stranded and double-stranded NA.  Different

choices of the potential correspond to the cases of active and passive opening.  An optimal choice of interaction potential leads to a helicase which 

can unwind NA as rapidly as it translocates on single strands.