Crystal structure of an enzymatically inactive trans-sialidase-like lectin from Trypanosoma cruzi: The carbohydrate binding mechanism involves residual sialidase activity

► First crystal structure of transialidase-like lectin iTS in complex with carbohydrate. ► The sialyl moiety is not visible in density, while lactose remains bound. ► iTS is confirmed to retain a residual sialidase activity by enzyme kinetics assays. ► iTS is able to bind sialylated glycoproteins as measured by surface plasmon resonance. ► The molecular details explain the lectin behavior of this trypanosomal protein family.