- Characterization of a novel trans-sialidase of Trypanosoma brucei procyclic trypomastigotes and identification of procyclin as the main sialic acid acceptor. Pontes de Carvalho, L.C., Tomlinson, S., Vandekerckhove, F., Bienen, E.J., Clarkson, A.B., Jiang, M.S., Hart, G.W., Nussenzweig, V. J. Exp. Med. (1993)