beta-galactoside (CMP) alpha-2,3-sialyltransferase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: CMP-N-acetylneuraminate + beta-D-galactosyl-(1->3)-N-acetyl-alpha-D-galactosaminyl-R = CMP + alpha-N-acetylneuraminyl-(2->3)-beta-D-galactosyl-(1->3)-N-acetyl-alpha-D-galactosaminyl-R. [EC:2.4.3.4]

Beta-galactoside (CMP) alpha-2,3-sialyltransferase activity is a key enzymatic process in the biosynthesis of complex glycoconjugates, including glycoproteins and glycolipids. This enzymatic activity is catalyzed by a family of enzymes known as sialyltransferases, specifically those that transfer sialic acid (N-acetylneuraminic acid, Neu5Ac) from the donor substrate CMP-sialic acid to the acceptor substrate beta-galactoside. The resulting product is a sialylated glycoconjugate with an alpha-2,3 linkage between the sialic acid and the galactose residue. This specific linkage is crucial for the biological functions of many glycoconjugates, including cell adhesion, cell signaling, and immune recognition. The enzyme active site exhibits high specificity for both the donor and acceptor substrates, ensuring the precise addition of sialic acid to the correct position on the glycoconjugate. This specificity is achieved through a combination of amino acid residues that interact with the substrates and contribute to the formation of a transient enzyme-substrate complex. The catalytic mechanism of the reaction involves the transfer of sialic acid from CMP-sialic acid to the hydroxyl group of the galactose residue, accompanied by the release of CMP. This process is highly regulated, influenced by factors such as the availability of substrates, the presence of cofactors, and the expression levels of the sialyltransferase enzyme. Dysregulation of this enzymatic activity can lead to a variety of pathological conditions, including cancer, inflammation, and autoimmune diseases. The study of beta-galactoside (CMP) alpha-2,3-sialyltransferase activity provides valuable insights into the complex process of glycoconjugate biosynthesis, its role in cell function, and its potential implications for human health.'
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Proteins (2)

Compounds (11)