STRUCTURAL TRANSFORMATION IN THE COLLAPSE TRANSITION OF THE SINGLE FLEXIBLE HOMOPOLYMER MODEL

The structural transformation in the coil-globule transition of a sing le flexible lattice chain has been investigated using dynamic Monte Ca rlo simulations. The results based upon ensemble averaging illustrated that for the homopolymers with Limited chain length; an intermediate state with a dense-core and molten-shell structure reversibly occurs i n the transition region. It was attributed to a special microphase sep aration behavior in an isolated coil, performing with densifying the d ense core and contracting the thin shell. The continuous appearance of the size transition and its tendency to discontinuity at the theta te mperature with the chain length approaching infinity were illustrated by the coexistence curves of the monomers with limited chain length. A possible explanation and its implications to the general mechanism of protein folding are also discussed. (C) 1998 American Institute of Ph ysics.