SUBCELLULAR-LOCALIZATION OF THE ENZYMES OF THE ARGININE DIHYDROLASE PATHWAY IN TRICHOMONAS-VAGINALIS AND TRITRICHOMONAS-FETUS

The enzymes of the arginine dihydrolase pathway were demonstrated in T ritrichomonas foetus and their subcellular localization determined for both T. foetus and Trichomonas vaginalis. Ornithine carbamyltransfera se (anabolic and catabolic activities), ornithine decarboxylase and ca rbamate kinase activity were localized predominately (56-80%) in the n on sedimentable fraction of both species. A large proportion (35-40%) of the arginine deiminase was, however, recovered in the large granula r fraction, and this distribution was unchanged by increasing the ioni c strength of the buffer. Upon density gradient centrifugation the par ticles containing arginine deiminase activity had an isopycnic density of 1.09 g/ml in percoll, and separated from hydrogenosomes (1.18 g/ml ) and lysosomes (1.12 g/ml). Arginine deiminase was also the only enzy me of the dihydrolase pathway which demonstrated latency upon treatmen t of the 1.09 g/ml fraction with non-ionic detergents. The results dem onstrate the presence of the arginine dihydrolase pathway in T. foetus and indicate that at least a portion of the arginine deiminase in tri chomonads is membrane associated.