Computational Chemistry and Molecular Modeling
Atomic, Molecular and Optical Physics
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
The growth-regulating factor MDGI belongs to the fatty acid binding proteins of which the amino acid sequence is known. Starting from hydrodynamic and dichroic measurements which yield estimations about mass, diameter, thickness, and content of α and β structure of the MDGI protein, we used theoretical methods to calculate the structures and electrostatic properties of selected β-chain sequences. The hydrophobic character of possible binding sites for fatty acids is demonstrated by the molecular electrostatic potential and field of this structures. A nonstandard turn element, formed by an H-bridge between polar side chains, Lys-Leu-Gly-Val-Glu, which connects two extended β chains, was found. Bound oleic acid could be able to stabilize such turn structure, which seems to appear also at the entrance of the cavity of two other proteins. The optimization of an oleic acid-turn van der Waals complex results in an interaction energy of about -50 kJ/mol originating mainly from the dispersion term and shows the participation of the four hydrophobic side chains Phe 64, Leu 66, Val 68, and Phe 70. Of these, at least Phe 64 and Phe 70 are known as possible binding sites of fatty acids.
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