In vivo incorporation of isotopically labelled amino acids into vertebrate proteins: L-[Me-3H]methionine incorporation into chicken egg white lysozyme.

The in vivo incorporation of L-[Me-3H]methionine into egg white lysozyme of the laying hen has been examined. Using a versatile synthetic chicken diet which consisted of 75% free amino-acid ration and 25% normal laying ration, 5-8% incorporation of the [3H]methionine into lysozyme was demonstrated. The utility of this vertebrate in vivo incorporation technique is discussed in terms of its application to the incorporation of 13C-enriched amino acids into vertebrate proteins as a prelude to macromolecular 13C nuclear magnetic resonance studies.