Analysis of free amino acids in mammalian brain extracts

An optimized method for analysis of free amino acids using a modified lithium-citrate buffer system with a Hitachi L-8800 amino acid analyzer is described. It demonstrates clear advantages over the sodium-citrate buffer system commonly used for the analysis of protein hydrolysates. A sample pretreatment technique for amino acid analysis of brain extracts is also discussed. The focus has been placed on the possibility of quantitative determination of the reduced form of glutathione (GSH) with simultaneous analysis of all other amino acids in brain extracts. The method was validated and calibration coefficient (K (GSH)) was determined. Examples of chromatographic separation of free amino acids in extracts derived from different parts of the brain are presented.