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This study was carried out to observe the activities and their distributions of several enzymes in Fasciola hepatica. The whole body homogenate was separated into cytosolic, mitochondrial and nucleic fractions by differential centrifugation. The activities of enzymes, NAD-linked α-glycerophosphate dehydrogenase(EC 1.1.1.8), FAD-linked isocitrate dehydrogenase(EC 1.1.1.42), trehalase(EC 3.2.1.28), branched chain amino acid aminotransferase(EC 2.6.1.24) and adenosine deaminase(EC 3.5.4.4) were measured in each fraction. The results were summarized as follows: 1. The activity of NAD-linked α-glycerophosphate dehydrogenase in cytosolic fraction was observed to be 1,998 units per one gram wet tissue, 93% of total activity and its specific activity was 2.1. The activity of FAD-linked α-glycerophosphate dehydrogenase in mitochondrial fraction was founded to be 39 units per one gram of wet tissue. It was fall under 67% of total activity and specific activity was 1.3. The rate of oxidation of α-glycerophosphate dehydrogenase by NAD- and FAD-linked α-glycerophosphate dehydrogenase were remarkable differed. This result indicates that transportation of reducing equivalents into mitochondria from the cytosol does not active. 2. The activity of NAD-linked isocitrate dehydrogenase was not detected in Fasciola hepatica whereas the NADP-linked isocitrate dehydrogenase was existed in both cytosolic and mitochondrial fraction. There activities were comparatively low. Therefore the Krebs cycle seems to be not active in Fasciola hepatica. NADPH produced by the action of NADP-linked isocitrate dehydrogenase may be utilized in the synthesis of fatty acids. 3. Relatively high activity of branched chain amino acid aminotransferase was observed in all fractions, and 81~87% of total activity was localized in cytosolic fraction. The best substrate of the branched chain amino acid aminotransferase among the three amino acids(leucine, valine and isoleucine) was isoleucine, and the worst was valine. 4. The activity of trehalase was not detected, it suggested that trehalose was not utilized by fasciola hepatica. 5. Deamination of adenosine by deaminase was not found.
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