The Amino Acid Assay Subcore provides investigators access to a number of analytical methods related to the measurement of labelled and unlabelled amino acids. The subcore provides space, equipment and personnel for sample analysis and method development. Investigators pay a charge to cover the cost of supplies and pro-rated service contracts. The analyses available include 1) complete amino acid profiles, 2) select amino acid profiles (branched chain or gluconeogenic), 3) amino acid specific activity determinations (alanine, leucine, phenylalanine) and 4) amino acid enrichment (leucine, alpha ketoisocaproate, phenylalanine). With the exception of the rapid assay for leucine and phenylalanine, the user group identified as being associated with this subcore project an increased need for all services offered.