Abstract
Rats fed 7% casein as the sole source of protein were divided into eight groups. Two of these were controls receiving an extra 1% casein. The remaining groups were fed equal amounts of a diet containing 1% of the following dl amino acids; isoleucine, methionine, phenylalanine, leucine, lysine or tryptophane. At the end of 3 weeks feeding all the animals were killed after a 24-hour fast and the enzyme activities in the pancreases were determined. It was found, by comparison with the controls, that no amino acid supplement increased amylase. Methionine increased lipase and protease activity and phenylalanine and isoleucine increased protease activity alone.