Presence and subcellular localization of tyrosine aminotransferase and p-hydroxyphenyllactate dehydrogenase in epimastigotes of Trypanosoma cruzi

Cell-free extracts of epimastigotes of Trypanosoma cruzi contain tyrosine aminotransferase (TAT) and p-hydroxyphenyllactate dehydrogenase (pHPLDH). The TAT activity could be separated from aspartate aminotransferase (ASAT) by polyacrylamide gel electrophoresis or DEAE-cellulose chromatography; the latter procedure also allowed complete separation of pHPLDH. The subcellular localization of both T. cruzi enzymes, as determined by digitonin extraction, subcellular fractionation by differential centrifugation, and isopycnic ultracentrifugation in sucrose gradients, was mainly cytosolic, with low mitochondrial activities.