Phenylalanine metabolism in Microtus montanus chronically infected with Trypanosoma brucei gambiense

1. Alterations in phenylalanine metabolism were observed in Microtus montanus infected with Trypanosoma brucei gambiense. 2. Reductions were found in the incorporation of phenylalanine into free amino acid pools and into proteins of the liver and other organs of infected animals. 3. Increased quantities of phenylpyruvate, 4-hydroxyphenylpyruvate and pyruvate were found in the urine of infected Microtus. 4. There appeared to be very limited conversion of phenylalanine to tyrosine in infected animals. This suggested that either phenylalanine transaminase activity was greatly elevated in proportion to phenylalanine hydroxylase activity; or that phenylalanine hydroxylase activity was actually reduced during the infection.