Molecular dynamics simulation of alpha-melanocyte stimulating hormone
in a water-membrane model interface

Pascutti PG, El-Jaik LJ, Bisch PM, Mundim KC, Ito AS

EUROPEAN BIOPHYSICS JOURNAL WITH BIOPHYSICS LETTERS
28: (6) 499-509 1999

Cited References:  25                Times Cited : 0

Abstract:
The conformation of the tridecapeptide alpha-melanocyte stimulating hormone in the presence of a double water-membrane interface was studied by molecular dynamics simulation, using the computational package THOR. In this program the solvent is represented by a continuous medium with dielectric constant epsilon, and the interface between different media is simulated by a surface of discontinuity of the dielectric constant. The electrostatic image method was used to write down the terms, added to the force field, that describe the polarisation effects induced in the interface by the atomic charges. The program was further improved by the introduction of a second surface, parallel to the first one, to mimic the membrane. A conformational search using the software Prelude was employed to find an initial geometry for the peptide in water. The molecular dynamics simulation performed during 10 ns showed that the peptide structure is flexible in water, without stabilisation of any preferential conformation. In the presence of the model membrane, the peptide moved to the medium representing the interior of the membrane. Inside the low dielectric constant medium, the structure of the peptide showed a turn in the central sequence of amino acids and a packed conformation remained stabilised during more than 7.0 ns of simulation.

Author Keywords:
melanotropic peptides, peptide-lipid interaction, dielectric discontinuity, molecular dynamics, electrostatic image method

KeyWords Plus:
MELANOTROPIC PEPTIDES, ANALOGS, DESIGN, MSH, PREDICTION, RECEPTOR, RESIDUES, CLONING

Addresses:
Ito AS, Univ Sao Paulo, Inst Fis, Caixa Postal 66318, BR-05315970 Sao Paulo, Brazil.
Univ Sao Paulo, Inst Fis, BR-05315970 Sao Paulo, Brazil.
Univ Fed Rio de Janeiro, Inst Biofis Carlos Chagas Filho, BR-21941 Rio De Janeiro, Brazil.
Ctr Brasileiro Pesquisas Fis, Rio De Janeiro, Brazil.
Univ Fed Bahia, BR-41170290 Salvador, BA, Brazil.

Publisher:  SPRINGER VERLAG, NEW YORK
IDS Number:  233LQ
ISSN:  0175-7571