neuraminidaas

Neuraminidase, also known as sialidase, is an enzyme that removes sialic acid residues from glycoconjugates such as glycoproteins and glycolipids. It is produced by a variety of organisms, including humans, bacteria, and many viruses, and it plays diverse roles in physiology and disease. In humans, there are several neuraminidases (often labeled NEU1–NEU4) that differ in cellular localization and function, such as degradation of sialylated proteins in lysosomes, regulation of cell signaling, and remodeling of the glycocalyx on the cell surface.

In pathogens, neuraminidases contribute to virulence and adaptation. Viral neuraminidase is one of the two major surface glycoproteins of influenza viruses, the other being hemagglutinin. Viral neuraminidase cleaves sialic acid from host cell receptors and mucus, enabling release of newly formed virions and helping the virus spread through the respiratory tract. Bacterial neuraminidases, found in species such as certain streptocci and many gut bacteria, can expose underlying receptors to promote adhesion or provide access to bound nutrients by liberating sialic acid from host glycoconjugates.

Mechanistically, neuraminidases hydrolyze the glycosidic bond between sialic acid and the adjacent sugar, a reaction that is facilitated by a conserved active site and is sensitive to transition-state analogs. This has made neuraminidases attractive targets for pharmacological intervention, particularly in influenza treatment. Neuraminidase inhibitors, including oseltamivir, zanamivir, and peramivir, block the enzymatic activity, reducing viral spread and disease severity. Resistance can arise through genetic changes in the neuraminidase gene or compensatory mutations in the virus.

In addition to medicine, neuraminidases influence host–microbe interactions and immune recognition, reflecting their broad relevance across biology and medicine.