Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21 944970, Cidade Universitaria, Ilha do Fundao, Rio de Janeiro, Brasil, E-mail: previato{at}biof.ufrj.br
Received on June 15, 2004; accepted on June 30, 2004
Key words: sialic acid / sialyllactitol / trans-sialidase
I read with interest the recent paper by Augustí et al. in the July 2004 issue of Glycobiology titled "Lactose derivatives are inhibitors of Trypanosoma cruzi trans-sialidase activity toward conventional substrates in vitro and in vivo" (Agusti et al., 2004). I was surprised with the authors' statement that
-2,3-sialyllactitol was unable to act as a donor substrate for T. cruzi trans-sialidase catalyzed reactions. We previously reported in an article published in Molecular Biochemical Parasitology (Previato et al., 1985
) that
-2,3-sialyllactitol was a donor substrate for the enzyme. To address these apparent conflicting results, we further investigated, as we did 20 years ago, whether the ability of wheat germ agglutinin to agglutinate neuraminidase-treated T. cruzi epimastigote forms was fully restored after incubation of such cells with
-2,3-sialyllactitol. The results obtained are in complete agreement with our prior conclusions that
-2,3-sialyllactitol was a good donor substrate. We next monitored, by high-performance anion exchange chromatography with pulsed amperometric detection the ability of
-2,3-sialyllactitol to act as donor substrate for the trans-sialidase using lactose as acceptor. As can be seen in Figure 1, contrasting with the observations of Augusti et al. (2004), we found that
-2,3-sialyllactitol was a donor-substrate for trans-sialidase.
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References
Agusti, R., Paris, G., Ratier, L., Frasch, A.C., and de Lederkremer, R.M. (2004) Lactose derivatives are inhibitors of Trypanosoma cruzi trans-sialidase activity toward conventional substrates in vitro and in vivo. Glycobiology, 14, 659670.
Previato, J.O., Andrade, A.F., Pessolani, M.C., and Mendonca-Previato, L. (1985) Incorporation of sialic acid into Trypanosoma cruzi macromolecules. A proposal for a new metabolic route. Mol. Biochem. Parasitol., 16, 8596.[CrossRef][ISI][Medline]
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