PREPARATIVE ISOLATION OF 9 INDISPENSABLE AMINO-ACIDS FROM A SINGLE-SAMPLE

In order to measure low isotopic labelling of amino acids with an acce ptable precision, the isolation of large amounts of amino acid is requ ired. When this is the case, the size of the original sample can be a limitation and usually labelling in only one amino acid can be measure d; the rest going to waste. By modifying existing methods, we have dev eloped a method in which nine indispensable amino acids can be isolate d by ion-exchange chromatography from a single sample. Protein hydroly sates containing up to 10 mu mol lysine were fractionated on a system that isolated lysine and histidine. The amino acids not resolved in th is system were also collected and methods for the isolation of valine, methionine, isoleucine, leucine, threonine, tyrosine and phenylalanin e from the same sample are described. (C) 1997 Elsevier Science B.V.