sialicacidbinding

Sialicacidbinding refers to the recognition and binding of sialic acid residues by proteins, enabling interactions with cell surfaces, pathogens, and immune receptors. Sialic acids are a family of acidic nine-carbon sugars, most commonly N-acetylneuraminic acid (Neu5Ac), that cap glycans on glycoproteins and glycolipids. They are typically found at terminal positions on N-linked and O-linked glycans and play roles in cell–cell communication, adhesion, and immune recognition.

Molecularly, sialicacidbinding involves specific interactions between a binding protein and the carboxylate, hydroxyl, and acetyl groups of the sialic acid. Binding specificity is influenced by the linkages connecting sialic acid to the underlying sugars, most notably α2-3, α2-6, or α2-8 linkages, as well as by the surrounding glycan context and the presence of different sialic acid variants, such as Neu5Gc or modified forms. Binding pockets in proteins are shaped to accommodate these features, often employing hydrogen bonds and salt bridges to stabilize the interaction.

Major protein families and examples include siglecs (sialic acid–binding immunoglobulin-like lectins), which are immune receptors that recognize sialylated ligands and can modulate immune responses; selectins, which bind sialylated ligands during leukocyte trafficking; and various microbial adhesins and viral glycoproteins, such as influenza hemagglutinin, that use sialic acid binding to attach to host cells. Sialidases (neuraminidases) are enzymes that remove sialic acids, illustrating the complementary nature of binding and cleavage in glycan biology.

Biological significance and applications include regulation of self versus non-self recognition, pathogen-host interactions, and tissue tropism. Therapeutic strategies often target sialicacidbinding to inhibit infection, modulate immune signaling, or alter cell adhesion, highlighting its relevance in immunology, virology, and glycobiology.