This chapter contains sections titled: Introduction Nonenzymic Degradation of Glutamine, Asparagine, and Glutathione Distribution of Glutamine, Asparagine, and Glutathione Asparagine and Glutamine Metabolism in Microorganisms Amide Metabolism in Plants Asparagine and Glutamine Metabolism in Intact Animals Glutamine Metabolism and Fertilization Glutathione Metabolism in Mammals Synthesis of Glutamine, Asparagine, and Glutathione Enzymic Splitting of Asparagine, Glutamine, and Glutathione