Cited References: 35     Times  Cited: 0

Abstract:
        The electrostatic image method was applied to investigate the conformation of peptides characterized by different hydrophobicities in a water-membrane interface model. The interface was represented by a surface of discontinuity between two media with different dielectric constants, taking into account the difference between the polarizabilities of the aqueous medium and the hydrocarbon one. The method consists of a substitution of the real problem, which involves the charges and the induced polarization at the surface of discontinuity, by a simpler problem formed with charges and their images. The electric field due to the polarization induced at the surface by charge q was calculated using a hypothetical charge q' (image of q), symmetrically located on the opposite side of the surface. The value of q' was determined using the appropriate electrostatic boundary conditions at the surface. By means of this procedure, the effect of the interface can be introduced easily in the usual force field. We included this extension in the computational package that we are developing for molecular dynamics simulations (THOR). The peptides studied included hydrophilic tetraaspartic acid (Asp-Asp-Asp-Asp), tetralysine (Lys-Lys-Lys-Lys), hydrophobic tetrapeptide (His-Phe-Arg-Trp), an amphiphilic fragment of beta-endorphin, and the signal sequence of the E. coli lambda-receptor. The simulation results are in agreement with known experimental data regarding the behavior of peptides at the water-membrane interface. An analysis of the conformational dynamics of the signal sequence peptide at the interface was performed over the course of a few nanoseconds. (C) 1999 John Wiley & Sons, Inc.

Author Keywords:
hydrophobic effect, molecular dynamics simulations, electrostatic image method, water-membrane model, beta-endorphin and signal sequence conformations

KeyWords Plus:
SIGNAL SEQUENCE, PROTEIN EXPORT, FLUORESCENCE, STABILITY, LIPIDS

Addresses:
Bisch PM, Fed Univ Rio De Janeiro, Inst Biofis Carlos Chagas Filho, BR-21949900 Rio De Janeiro, Brazil.
Fed Univ Rio De Janeiro, Inst Biofis Carlos Chagas Filho, BR-21949900 Rio De Janeiro, Brazil.
Univ Sao Paulo, Inst Fis, BR-01498 Sao Paulo, Brazil.
Univ Fed Bahia, Dept Fis, Salvador, BA, Brazil.

Publisher:  JOHN WILEY & SONS INC, NEW YORK
IDS Number:  204TU
ISSN: 0192-8651