The release of amino acids from rat-liver mitochondrial extract

• 1.1. The object of this investigation was to study the release of ninhydrin-reacting material, consisting largely of amino acids, which is found to occur during incubation of soluble extracts of rat-liver mitochondria at neutral pH.
• 2.2. The nature and proportions of the amino acids released at pH 7.4 and at pH 5.2 were found to be similar, although there were some differences for individual amino acids.
• 3.3. In contrast, the total amino acid composition of mitochondrial extract was found to differ considerably in respect to the proportions of certain amino acids, notably aspartic acid, glutamic acid, serine and thereonine, from that of the amino acid mixture liberated during incubations. It was concluded that the amino acids released during incubation are derived from only a portion of the protein in the mitochondrial extract.
• 4.4. In the presence of heated mitochondrial extract the quality of ninhydrinreacting material liberated by native extract during incubation was increased. It was concluded that heated extract could act as substrate for proteolytic enzymes in the native extract.
• 5.5. The participation of lysosomal proteolytic enzymes in bringing about the release of amino acids from mitochondrial extract even at pH 7.4 could not be excluded.