Intramitochondrial localization of the 4-aminobutyrate-2-oxoglutarate transaminase from ox brain

In order to determne the intramitochondrial location of 4-aminobutyrate transaminase, mitochondria were prepared from ox brain and freed from myelin and synaptosomes by using conventional density-gradient-centrifugation techniques, and the purity was checked electron-microscopically. Inner and outer membranes and matrix were prepared from the mitochondria by large-amplitude swelling and subsequent density-grient centrifugation. The fractions were characterized by using both electron microscopy and different marker enzymes. From the specific activity of the 4-aminobutyrate transaminase in the submitochondrial fractions it was concluded that this enzyme is associated with the innter mitochondrial membrane.