THE FREE AMINO ACIDS OF HUMAN SPINAL FLUID DETERMINED BY ION EXCHANGE CHROMATOGRAPHY

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Abstract
SUMMARY: (1) The free amino acids in human CSF from eighteen subjects have been determined. The analyses were performed on 0‐75 ml of CSF by an ion exchange chromatographic method which is capable of detection to the 10−10 mole level.(2) The amino acids always found in readily detectable amounts were: taurine, threonine, serine, glutamine, glutamic acid, citrulline, glycine, alanine, α‐NH2‐n‐ butyric acid, valine, methionine, isoleucine, leucine, tyrosine, phenylalanine, ethanolamine, ornithine, lysine, histidine and arginine. Urea was present. Aspartic acid and cystine, though always present, occurred in small or trace amounts. Proline was found in four cases and tryptophan in thirteen cases. In addition, twelve unknown peaks were nearly always evident in every chromatogram.(3) Filtrates 10 times more concentrated than those used regularly were prepared from pooled CSF and analysed. These analyses clearly confirmed the presence of those amino acids which were normally in very low concentration and they also served to distinguish the twelve unknown compounds from confusion with baseline artifacts.(4) The distribution of free amino acids in CSF was different from their distribution in blood plasma.(5) Despite a variety of neurological conditions and a wide age span few marked deviations were found in any of the amino acid concentrations.