Changes in carbamyl phosphate synthetase and ornithine transcarbamylase levels during development and in response to changes in diet. Application of the electrophoretic transfer technique.

We have investigated changes in the levels of carbamylphosphate synthetase and ornithine transcarbamylase in response to the protein content of the diet and during development using the electrophoretic transfer technique. Levels of carbamylphosphate synthetase increased from 3.01 +/- 0.21 mg/g liver to 8.80 +/- 0.46 mg/g liver in rats on diet containing 15% and 60% casein. The levels of ornithine transcarbamylase showed a smaller increase from 0.49 +/- 0.06 to 0.82 +/- 0.09 mg/g liver. Developmental patterns for these enzymes were also different: carbamylphosphate synthetase increased sharply from less than 0.01 mg/g liver at 15,16 and 17 days foetal age to 1.6 mg/g liver at birth and 4.9 mg/g liver in adults. Ornithine transcarbamylase increased gradually from 0.04 mg/g liver at 15 days foetal age to 0.23 mg/g liver at birth and 0.59 mg/g liver in adult liver. At no stage during development was the precursor form of either enzyme detected in liver extracts.