The overall objective of this project is to detect some property in the synthesis or the function of the mitochondria in African trypanosomes which will provide a tool for inhibiting the development and the replication of these parasites. In this way we hope to develop a more rational approach for developing and testing of potential trypanocidal compounds than now exists. Our specific aims for the period of the proposal are: 1. To isolate a purified preparation of mitochondria without other organelles. We hope to prepare either a preparation with only the refused mitochondria present or the complete mitochondrion-kinetoplast complex; 2. To characterize the branched electron transport system present in cyanide-sensitive trypanosomes as to what cytochrome and flavin components are present in the CN-sensitive and CN-insensitive pathway; 3. To identify the significance of two functional oxidases, cytochrome oxidase o and cytochrome aa3, in CN-sensitive trypanosomes; 4. To characterize what are the sequence of events during the synthesis of the electron transport system during the differentiation of T. brucei bloodstream stumpy form trypomastigotes to vector trypomastigotes; 5. To identify whether a functional RNA polymerase is present in the mitochondria of trypanosomes. This enzyme would be important for the synthesis of mitochondrial proteins and its inhibition effective in inhibiting the function of the mitochondria; 6. To study the effect of berenil, suramin, acriflavine and ethidium bromide on the replication and function of kinetoplast DNA and on the synthesis of the electron transport system.