Molecular dynamics analysis of conserved water mediated inter-domain recognition of His667-Trp669 in human ceruloplasmin.

The human ceruloplasmin (hCP) is the copper containing ferroxidase enzyme with multifunctional activities (NO-oxidase, NO2-synthase,oxidation of neurotransmitters including antioxidants). Therefore, it is of interest to probe the multi-domain hCP using moleculardynamics simulation. Results explain the role played by several conserved water centers in the intra and inter-domain recognition throughH-bond interaction with the interacting residues. We observed seventeen conserved water centers in the inter-domain recognition. Weshow that five invariant water centers W13, W14, W18, W23 and W26 connect the Domain 5 to Domain 4 (D5…W…W4). We also show thatfive other water centers W19, W20, W27, W30 and W31 connects the Domain 5 to Domain 6 (D5…W…W6) that is unique in the simulatedform. The W7 and W32 water centers are involved in the D1…W…W6 recognition. This is important for the water-mediated interaction ofGlu1032 to the trinuclear copper cluster present at the interface between these domains. The involvement of W10 water center in theD3…W10…D4 recognition through Gln552…W10…His667 H-bond interaction is critical in the complexation of CP with myeloperoxidase(Mpo). These observations provide insights to the molecular recognition of hCP with other biomolecules in the system.