Some psysicochemical properties of mitochondrial and cell sap alanine aminotransferase from the rat CNS.

The authors describe different properties of brain mitochondrial and cell sap alanine aminotransferase. They showed that the mitochondrial enzyme was inhibited by maleate, chlorides, acetate and phosphate with a high ionic strength (over 1.8), that its pH optimum lay between 7.5 and 8.5, that it was thermolabile at over 40 degrees C and that it was salted out from solutions with ammonium sulphate at 0.6--0.8 saturation. The activity of the cell sap enzyme was inhibited by phosphate at an ionic strength of only 0.12, less markedly by maleate and not at all by chlorides and acetate; its pH optimum was about 8, it was thermostable up to 60 degrees C and was precipitated from ammonium sulphate solution at between 0.35 and 0.6 saturation. The authors conclude from their results that two different alanine aminotransferase enzymes are present in the CNS.