Trypanosoma cruzi trans-sialidase. A tool for the synthesis of sialylated oligosaccharides

摘要

Cells are covered by a complex array of carbohydrates. Among them, sialosides are of key importance in intracellular adhesion, recognition and signaling. The need for structurally diverse sialosides impelled the search for efficient synthetic methods since their isolation from natural sources is a difficult task. The enzymatic approach obviates the need of a chemical synthesis for protecting or participating groups in the substrates. The trans-sialidase of Trypanosoma cruzi (TcTS) is highly stereospecific for the transfer of sialic acid from an alpha-sialylglycoside donor to a terminal beta-galactopyranosyl unit in the acceptor substrate to form the alpha-Neu5Ac-(2 -> 3)-beta-D-Galp motif. The enzyme was cloned and easily available glycoproteins, e.g. fetuin, may be used as donors of sialic acid, constituting strong points for the scalability of TcTS-catalyzed reactions.