The relationship between nutritive value of dietary protein and activity of liver arginase and kidney transamidinase enzymes

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Abstract
1. The protein efficiency ratio of three protein sources was determined with rats by a depletion-repletion method. The sources were: a groundnut product, a methionine-supplemented groundnut product and lactalbumin.2. Livers obtained from the test animals were assayed for arginase activity, and kidneys for transamidinase activity (glycine amidinotransferase).3. The measurements indicated that there was an inverse relationship between arginase activity and the nutritive value of the dietary protein.4. Transamidinase activity was also influenced by nutritive value. Only the unsupplemented groundnut product, which had the lowest nutritive value, failed to produce a significant increase of transamidinase activity over basal levels.5. The findings are discussed from the standpoint of physiological function and needs. It is suggested that observed levels of arginase activity are not necessarily related to amounts of urea excreted; similarly, transamidinase activity may be well in excess of physiological requirements.