FREE AMINO ACIDS IN TAY-SACHS AND NORMAL HUMAN BRAIN GRAY MATTER

Previous studies showed significant differences in the amino acid composition of the ganglioside-peptides in Tay-Sachs disease as compared to normal brain gray matter. The present study was undertaken to determine whether these differences in peptide composition could be related to variations in their free amino acid pools. About 31 amino acid peaks were obtained by means of automated ion-exchange column chromatography of which 27 were identified. The results obtained (moles of amino acid/100 moles of total amino acids) for autopsied normal brain gray matter agree well with previously published data except for higher values for taurine, threonine and glycine and a lower value for phosphoethanolamine. Comparison of free amino acid levels in Tay-Sachs brains with normals showed significantly decreased values for glutamic acid, aspartic acid and γ-aminobutyric acid and increased values for alanine, valine, leucine and tyrosine. No significant differences in free amino acid levels were found between samples from frontal, parietal and occipital lobes for either normal or Tay-Sachs brains. The possible relationship of the free amino acid changes in Tay-Sachs disease to ganglioside accumulation and to ganglioside-peptide amino acid composition is discussed. © 1968.