title: Nutritional and medicinal aspects of D-amino acids.
abstract: This paper reviews and interprets a method for determining the nutritional value of D-amino acids, D-peptides, and amino acid derivatives using a growth assay in mice fed a synthetic all-amino acid diet. A large number of experiments were carried out in which a molar equivalent of the test compound replaced a nutritionally essential amino acid such as L-lysine (L-Lys), L-methionine (L-Met), L-phenylalanine (L-Phe), and L-tryptophan (L-Trp) as well as the semi-essential amino acids L-cysteine (L-Cys) and L-tyrosine (L-Tyr). The results show wide-ranging variations in the biological utilization of test substances. The method is generally applicable to the determination of the biological utilization and safety of any amino acid derivative as a potential nutritional source of the corresponding L-amino acid. Because the organism is forced to use the D-amino acid or amino acid derivative as the sole source of the essential or semi-essential amino acid being replaced, and because a free amino acid diet allows better control of composition, the use of all-amino-acid diets for such determinations may be preferable to protein-based diets. Also covered are brief summaries of the widely scattered literature on dietary and pharmacological aspects of 27 individual D-amino acids, D-peptides, and isomeric amino acid derivatives and suggested research needs in each of these areas. The described results provide a valuable record and resource for further progress on the multifaceted aspects of D-amino acids in food and biological samples.
authors.affiliation: Western Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Albany, CA 94710, USA. mendel.friedman@ars.usda.gov
authors.forename: Mendel
authors.initials: M
authors.lastname: Friedman
authors.forename: Carol E
authors.initials: CE
authors.lastname: Levin
mesh_terms: D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D004032:Diet; D004044:Dietary Proteins / Q000378:metabolism; D006801:Humans; D007536:Isomerism; D051379:Mice; D009753:Nutritive Value; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D004044:Dietary Proteins; D010455:Peptides