Trans-Sialidase TS

Most information on how the trans-sialidase reaction proceeds was obtained from binding studies with either active T cruzi TS or with inactive natural mutants using surface plasmon resonance technology and NMR spectroscopy. While, for example, sialyllactose was readily bound to the enzyme protein, the acceptor substrate lactose or other asialo glycoconjugates did not interact with the enzyme at all unless it had been pre-incubated with the sialylated donor substrate. All of these studies clearly show that sialic acid modulates the afiSnity for die asialo acceptor substrate. The association of the asialo receptor with the active site is an... 

Two trans-sialidases isolated from the animal-pathogenic Afiican trypanosome T. Congo lense show pronounced differences in their capacity for sialic acid transfer as compared with the hydrolytic activity. Partial sequences were obtained from these two enzymes by a PCR-based approach, showing 50% identity with each oflier, but are similar to viral, bacterial, animal siahdases and other trans-sialidases. Most of the critical active-site residues common to other trypanosomal siahdases and TS are conserved This similarity, together with the amino acid difference at the active site, between American and African (trans-)siahdases is depicted in the pubUcation. ... 

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