TRYPANOSOMA-RANGELI SIALIDASE LACKS TRANS-SIALIDASE ACTIVITY

Extracts and tissue culture supernatants of axenic forms of T. rangeli were assayed for the presence of sialidase and trans-sialidase activi ties. Using sialyl(alpha 2-3)lactose, sialyl(alpha 2-6)lactose, poly(a lpha 2-8)N-acetylneuraminic acid, fetuin and 4-methylumbelliferyl-N-ac etylneuraminic acid as sialic acid donors, and lactose as a sialic aci d acceptor, no trans-sialidase activity was detected. Nevertheless, T. rangeli lysates and culture supernatants contain a sialidase that hyd rolyzes sialyl(alpha 2-3)lactose, and much less efficiently sialyl(alp ha 2-6)lactose, but not poly(alpha 2-8)N-acetylneuraminic acid. T. cru zi trans-sialidase hydrolyzed only sialyl(alpha 2-3)lactose under the same conditions. The T. rangeli and the T. cruzi enzymes differ antige nically and in their pH optimum for hydrolase activity.