Donor substrate binding to trans-sialidase of Trypanosoma cruzi as studied by STD NMR

Using STD NMR experiments, we have studied the binding epitopes of p-nitrophenyl glycosides of sialic acid and analogs thereof when bound to Trypanosoma cruzi trans-sialidase (TSia). Time-dependent NMR spectra yielded data on the rate of substrate hydrolysis in comparison to sialic acid transfer. Our experiments clearly demonstrate that shortening of the glycerol side chain significantly favors the transfer reaction over hydrolysis. Our results extend the basis on which specific trans-sialidase inhibitors may be designed.