Similarity of cruzin, an inhibitor of Trypanosoma cruzi neuraminidase, to high-density lipoprotein.

A specific inhibitor of the neuraminidase of the protozoan parasite Trypanosoma cruzi was isolated recently and named cruzin. It is now shown that cruzin is similar to high-density lipoprotein by amino acid homology, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, by immunoblot analysis, and by isoelectric focusing. Cruzin purified by ion exchange chromatography and high-density lipoprotein isolated by density gradient ultracentrifugation inhibited Trypanosoma cruzi neuraminidase to the same extent. Cruzin or high-density lipoprotein restores to normal the decreased multiplication rate of Trypanosoma cruzi epimastigotes grown in a medium depleted of lipoproteins, suggesting that it may be important for survival of the parasite in nature.