Piebald rats receiving a lysine-deficient diet containing gliadin as the sole protein grew when [epsilon]-acetyl lysine was provided, either orally or''parenterally, but not when the [alpha]-acetyl derivative was supplied. Methods are described for the synthesis of [epsilon]-carbobenzoxy lysine, [alpha]-N-acetyl lysine, and [epsilon]-N-acetyl lysine from the Cu complex of lysine.