Hyperphenylalaninemia: disaggregation of brain polyribosomes in young rats.

A single injection of l-phenzylalanine in 7-day-old rats produtced disaggregation of brain polyribosomties and inhibition of in vitro protein synthesis in cell-free systems prepared from brain. Liver polyribosomes and in vitro protein synthesis in hepatic systems were not affected. In 4-week-old rats these effects on brain protein synthesis did not occur.