STRUCTURAL ORGANIZATION OF LACTOFERROXIN MOLECULES

Abstract

The conformational possibilities of lactoferroxin A (H-Tyr1-Leu2-Gly3-Ser4-Gly5-Tyr6-OH) and lactoferroxin B (H-Arg1-Tyr2-Tyr3-Gly4-Tyr5-OH) molecules were studied by theoretical conformational analysis. The potential energy of the system is chosen as the sum of non-valence, electrostatic and torsion interactions and the energy of hydrogen bonds. The low-energy conformations of molecules, the dihedral angles of the main and side chains of amino acid residues that make up the molecule were found, and the energy of intra- and interresidual interactions was estimated. It is shown that the spatial structure of the lactoferroxin A molecule is represented by fourteen forms of the main chain, and the spatial structure of the lactoferroxin B molecule by eleven forms of the main chain. Comparison of the obtained low-energy conformations of lactoferroxins A and B shows that they have quite a lot in common. In a small energy range of 0–3,0 kcal/mol, these molecules have many conformations. Therefore, it is precisely this that explains the fact that both molecules perform a common biological function. It can be assumed that tyrosine amino acid residues are involved in the performance of the biological function. In similar conformations, their side chains in space are approximately in the same positions. The results obtained can be used to elucidate the structural and structural-functional organization of lactoferroxin molecules.