Manganese binding to antioxidant peptides involved in extreme radiation resistance in Deinococcus radiodurans.

A decapeptide, DEHGTAVMLK (DP1), and its random scrambled version, THMVLAKGED (DP2), have been studied for their interactions with manganese. The amino acid composition of the peptides was selected to include the majority of the most prevalent amino acids present in a Deinococcus radiodurans bacterium cell-free extract that contains components capable of conferring extreme resistance to ionizing radiation. The extract appears to be rich in Mn(II) complexes which seem to be responsible for protecting proteins from Reactive Oxygen Species damage. We focused our attention on the interaction of the decapeptides with Mn(II) ion with the aim of obtaining information on the possible complexes formed, by using NMR, EPR, and ESI-MS techniques.