Abstract 1. 1. The synthesis of three peptide derivatives which contain lysine is described. These include benzoyl- l-lysylglycine, benzoyl- l-lysine hydrochloride, and benzoylglyeyl- l-lysine. In addition, a number of new derivatives of lysine are described. 2. 2. These peptide derivatives together with some previously prepared compounds have been employed in a study of the effects of the ϵ- N-lysine-glucose reaction on proteolytic digestion. 3. 3. Following the reaction of the ϵ-amino group of lysine with glucose, very definite changes occur in the susceptibility to pancreatic digestion of peptide linkages of the α-amino and carboxyl groups of the lysine residue. 4. 4. The observations support a hypothesis that the decrease in nutritive value of proteins which have been cooked, heated, or stored with reducing sugars is primarily a result of incomplete digestion by pancreatic enzymes.