sialylaation

Sialylation is a biochemical process involving the enzymatic addition of sialic acid (commonly N-acetylneuraminic acid, Neu5Ac) to glycoconjugates, such as glycoproteins and glycolipids. This post-translational modification plays a critical role in cellular recognition, signaling, and immune responses. Sialic acids are nine-carbon sugars found at the terminal positions of oligosaccharide chains, where they often cap glycans and influence their biological functions.

The process is catalyzed by sialyltransferases, a family of glycosyltransferases that transfer sialic acid from activated donors, typically cytidine monophosphate-N-acetylneuraminic acid (CMP-Neu5Ac), to specific acceptor molecules. Different sialyltransferases exhibit substrate specificity, determining the linkage type (e.g., α2,3, α2,6, or α2,8) and the resulting glycan structure. These variations contribute to the diversity of sialylated glycans, which can affect protein folding, stability, and interactions with receptors.

Sialylation is widely distributed across eukaryotic organisms and is essential for various physiological processes. In the immune system, sialylated molecules can modulate inflammation and pathogen recognition, while in cancer, altered sialylation patterns are often associated with metastasis and immune evasion. Additionally, sialic acids are involved in cell-cell adhesion, neuronal signaling, and viral attachment, highlighting their broad biological significance.

Disruptions in sialylation have been linked to diseases, including neurodegenerative disorders, infections, and metabolic syndromes. Research into sialylation mechanisms and its regulatory pathways continues to provide insights into potential therapeutic targets, particularly in oncology and infectious disease treatment. Synthetic biology and glycoengineering approaches are also being explored to manipulate sialylation for biomedical applications.