l-CYSTATHIONINE IN HUMAN BRAIN

Abstract

During the course of the study of the distribution of N-acetylaspartic acid in brains of different species (1, 2), protein-free extracts of brain tissues were analyzed specifically for the aspartic acid derivative. In pursuing these investigations further, a survey was made by ion exchange chromatography of the concentration of all of the free acidic and neutral amino acids of the brain tissues, in a manner similar to that previously employed for study of the ninhydrin-positive constituents of the various tissues of the cat (3). The present investigation began when a striking difference was observed between the effluent curve obtained when an extract of human brain was analyzed and that found earlier (3) for cat brain. A major ninhydrin-positive peak was present in the region of the chromatogram between the valine and the methionine positions. Large amounts of material emerging at this effluent volume were not found either in the other brain extracts or in the other cat tissues previously analyzed. The present communication is concerned with the identification of the compound responsible for this peak on the chromatograms of the extracts of human brain.