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https://www.arca.fiocruz.br/handle/icict/19476
TRYPANOSOMA CRUZI TRANS-SIALIDASE AND NEURAMINIDASE ACTIVITIES CAN BE MEDIATED BY THE SAME ENZYMES
Afiliação
Escola Paulista de Medicina. São Paulo, SP, Brasil
New York University Medical Center. Department of Pathology and Kaplan Cancer Center. New York, New York
New York University Medical Center. Department of Pathology and Kaplan Cancer Center. New York, New York
New York University Medical Center. Department of Pathology and Kaplan Cancer Center. New York, New York
New York University Medical Center. Department of Pathology and Kaplan Cancer Center. New York, New York
Resumo em Inglês
Trans-sialidase and neuraminidase activities have been detected on the surface membrane of
trypomastigotes of Trypanosoma cruzi, and both have been implicated in the parasite's invasion
of host cells. We show here that these enzymes are structurally related. They are recognized
by two independently derived monoclonal antibodies, are anchored to the membrane by
glycosylphosphatidylinositol, copurify by ion exchange, molecular sieving, and hydrophobic
chromatography, have maximal activities between pH 6.5 and 7.5, and are inactivated by heating
at 56~ Furthermore, the neuraminidase and trans-sialidase reactions are coupled. An increase
of the concentration of acceptors of the transfer reaction decreases the amount of flee sialic acid
released through the neuraminidase reaction. We conclude that a single enzyme can catalyze
the transfer or the hydrolysis of macromolecular-bound sialic acid. The predominant direction
of the reaction will depend on the availability of appropriate oligosaccharide acceptors of sialic acid.
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