Abstract
Human eosinophil cationic protein (hECP) is a heparin-binding ribonuclease secreted by activated eosinophils. ECP is a basic, granule-stored protein known to be cytotoxic toward pathogens and several cell lines involved in the immune innate system. The mechanism of ECP internalization is including HS binding ability and lipid raft-associated micropinocytosis. Previous studies have discovered that the sequence motif 32NYRWRCKNQN41 of ECP was defined to possess in heparin binding and cell penetrating activities, while motif 32NYRWRCKN39 have been proven to bind with dodecylphosphocholine micelle. The binding between ECP32-41 (NYRWRCKNQN) and heparin was previously characterized, but the detail of binding mechanism is still unclear. To achieve the goal, we have used nuclear magnetic resonance (NMR) to evaluate the binding of ECP32-41、ECP32-41 W4R and EDN32-41 and to heparin. Additionally, we also investigated the tryptophan of ECP32-41 leading the interaction with membrane.