Shield and bridge: Dual functions of glycan chains in ovomucin structure stability and gel network formation

Ovomucin (OVM) is a key protein in egg white responsible for gel formation, with high glycosylation. To understand the association of glycosylation with OVM gelation capacity and structure stability, the effects and mechanisms of different glycan chains and monosaccharides on OVM gel properties were systematically investigated in this study. The results showed that removal of O-glycan chains rendered OVM completely incapable of gelation, whereas N-glycan chain removal reduced the cross-linking density of gel networks. Modification of OVM with neutral monosaccharides significantly enhanced the mechanical properties of gel, mainly attributed to the enhancement of disulfide and hydrogen bonds. The moderate presence of sialic acid (SA) facilitated the formation of OVM gels by regulating the molecular spacing via electrostatic forces. However, excess SA destabilized the gel network. In addition, the glycosylation sites and glycan chain composition of OVM were analyzed by LC-MS/MS, and the protective effect of OVM glycan chains to its own molecular structure under strong alkaline environment was revealed. Computational biology further validated the enhancement of intermolecular interactions by glycosylation. This study proved the crucial regulatory role of OVM glycosylation structure on its gel properties, providing a new insight into the strategy of modulating functional properties of proteins through glycosylation modifications.