The study of amino acids has come to be recognized during recent years as a subject of tremendous importance, on account of its fundamental relation to the problems of human and animal nutrition. Not many years since, all proteins were thought to be of equal nutritive value. Now we know that many of the proteins are deficient in one or more amino acids, and cannot support life and growth unless supplemented by other proteins which make up the deficiency. And from a study of the proteins with reference to their amino acid make-up, the study of the amino acids themselves began to occupy the attention of chemists. Thus after the chemist had taken the protein molecule apart and identified the various amino acids of which it was composed, he undertook to synthesize these amino acids from simple substances, to separate the synthetic products into their optically active components, prepare numerous derivatives, and finally to study their behavior toward biological processes of both animal and vegetable nature
