N-Glycans Stabilize Human Erythropoietin through Hydrophobic Interactions with the Hydrophobic Protein Surface: Studies by Surface Plasmon Resonance Analysis

Abstract

Human erythropoietin (EPO) produced in Chinese hamster ovary cells is a hydrophobic protein highly stabilized by multibranched complex-type N-glycans. To reveal the molecular basis of the interaction between the N-glycans and the EPO protein, complex-type N-glycans of different structures were analyzed as to their binding affinity for Escherichia coli-expressed EPO by means of the surface plasmon resonance technique. It appears well established that complex-type N-glycans, particularly multibranched ones, have hydrophobic regions that extensively stretch across the plane holding acetylamino groups and that N-glycan-protein hydrophobic interactions characterized by a slow rate of dissociation stabilize the protein conformation.