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Glycobiology Advance Access originally published online on July 7, 2004
Glycobiology 2004 14(10):25G; doi:10.1093/glycob/cwh124
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Glycobiology vol. 14 no. 10 © Oxford University Press 2004; all rights reserved.

Letter to the Glyco-Forum

{alpha}-2,3-Sialyllactitol is a donor substrate for Trypanosoma cruzi trans-sialidase

Jose O. Previato

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., 2004Go). I was surprised with the authors' statement that {alpha}-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., 1985Go) that {alpha}-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 {alpha}-2,3-sialyllactitol. The results obtained are in complete agreement with our prior conclusions that {alpha}-2,3-sialyllactitol was a good donor substrate. We next monitored, by high-performance anion exchange chromatography with pulsed amperometric detection the ability of {alpha}-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 {alpha}-2,3-sialyllactitol was a donor-substrate for trans-sialidase.



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  		Fig. 1. HPAEC-PAD of the trans-sialidase reaction products obtained using {alpha}-2,3-sialyllactitol and lactose as substrates. The reaction was at 28°C in a final volume of 100 µl of Tris–HCl buffer, pH 7.4 containing 0.8 mU trans-sialidase, 100 nmol {alpha}-2,3-sialyllactitol, 200 nmol lactose, and 50 nmol 2-keto-3-deoxyoctonate (KDO) as internal standard. At times zero (A), 10 min (B), 20 min (C), and 30 min (D), aliquots (20 µl) were removed, diluted into 100 mM NaOH, and chromatographed on a CarboPac PA-10 column eluted with 50 mM NaOAc in 100 mM NaOH for 10 min followed by a linear gradient from 50 to 80 mM NaOAc in NaOH over 25 min. The flow rate was 1 ml/min. The elution positions of lactitol (1), lactose (2), sialyllactitol (3), KDO (4), and sialyllactose (5) are indicated.

 
In conclusion, our current results fully support our previous report that {alpha}-2,3-sialyllactitol is able to act as donor substrate for trans-sialidase of T. cruzi.

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, 659–670.[Abstract/Free Full Text]

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, 85–96.[CrossRef][Web of Science][Medline]


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This Article
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