Inhibitory effect of taurolipids on Clostridium perfringens sialidase

Taurolipids A and B, which are detergent-type compounds isolated from protozoan Tetrahymena cells, were demonstrated to inhibit strongly the activity of Clostridium perfringens sialidase. On addition of 280 pmol of taurolipid B to 20 mU of the enzyme, the sialidase activity was decreased to 7% of the original activity at pH 5.1 as the optimum pH. The inhibition was non-competitive. Effective inhibition was observed at the acidic region from the isoelectric point of the sialidase, and at a low ionic strength. Both the long chain acyl and sulfonic acid groups of taurolipids were required for the inhibition of the sialidase activity. A mechanism is postulated for the inhibition.