Alanine and aspartate aminotransferase activities in serum and various subcellular fractions from the livers of different species

Abstract

1. 1. Aspartate aminotransferase activity in serum and liver mitochondria and cytosols of rats, guinea-pigs, chickens and cattle was considerably higher than alanine aminotransferase activity. 2. 2. Chicken liver mitochondrial aspartate aminotransferase activity was 6% of the total activity found in the cytosol and remained like the chicken liver cytosol ASPT activity, unchanged after sonication, and could not be attributed to absorption of any cytosol enzyme. 3. 3. K m values of chicken liver mitochondrial and cytosol aspartate aminotransferases and rat liver aspartate aminotransferase for α-ketoglutarate were 0.22, 0.24 and 0.23 mM respectively. 4. 4. Chicken liver mitochondrial and cytosol aminotransferase activities were destroyed to the same extent when heated to the same temperatures. 5. 5. Conversion of aspartate into blood glucose was observed with fasted rats and guineapigs, but not with fasted chickens.