Inhibitory Effect of Mercaptoamino Acids on Lysinoalanine Formation During Alkali Treatment of Proteins

Abstract
Alkali treatment of food proteins converts some amino acid residues to the unnatural amino acid lysinoalanine which has been found to cause kidney damage when fed to rats. Formation of lysinoalanine was essentially prevented when isolates of soy protein and casein were exposed to alkali in the presence of thioalamino acids such as cysteine. The results suggest that added thiols minimize the formation of potentially toxic lysinoalanine.