Trypanosoma cruzi trans-sialidase: a tool for multisialylation of β-thio-glycoclusters

CANO, ME; MUCHNIK DE LEDERKREMER, R; AGUSTI, R; KOVENSKI J; CAGNONI, A.; UHRIG, M.L.

New Orleans

Simposio; XXVIII International Carbohydrate Symposium; 2016

International Carbohydrate Society

Multivalent glycoclusters have been synthesized inorder to obtain high affinity ligands for specific binding to cellularproteins. Multivalency is most frequently achieved by the simultaneous attachmentof several protected sugar fragments to a suitable functionalized scaffold andthe copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC), also known as the clickreaction, has proved to be highly convenient for this purpose. On the otherhand, the synthesis of glycoclusters exposing a-sialic acid residues remains an active area ofresearch since sialic acid plays an important role in a variety of biologicalprocesses including viral and bacterial adhesion. They have a potential foranti-adhesion therapies and would help to elucidate the features involved incarbohydrate-protein interactions.Thesynthesis of multivalent sialylated glycoclusters is herein addressed by achemoenzymatic approach using the trans-sialidase of Trypanosom cruzi(TcTS). Multivalent b-thio-galactopyranosides and b-thio-lactosideswere used as acceptor substrates and 3?-sialyllactose as the sialic acid donor.High performance anion exchange chromatography with pulsed amperometricdetection (HPAEC-PAD) was shown to be an excellent technique for the analysis of thereaction products. Different eluting conditions were optimized to allow thesimultaneous resolution of the sialylated species, as well as their neutralprecursors.The TcTS efficiently transferred sialyl residues to di, tri, tetra andocta b-thiogalactosides. In the case of an octavalentthiolactoside, up to six polysialylated compounds could be resolved. Preparativesialylation reactions were performed using the tetravalent and octavalentacceptor substrates. The main sialylated derivatives could be unequivocallyassigned by MALDI mass spectrometry. Inhibition of the transfer to the naturalsubstrate, N-acetyllactosamine, wasalso studied. The octalactoside caused 82 % inhibition of sialic acid transferwhen we used equimolar concentrations of donor,acceptor and inhibitor.