Comparative studies on the human glutamate-pyruvate transaminase phenotypes--GPT 1, GPT 2-1, GPT 2.

The quantitative differences between the activity of the 3 common phenotypes of human red cell GPT has been confirmed. In addition, the activity of red cell GPT 1 was found to be greater in young children than in adults. No such difference was found for the GPT 2 phenotype. The activity of the red cell GPT 1 was found to decrease with age, reaching the adult level at the age of 10 to 12 years. Red cell GPT of all the 3 common phenotypes in both adults and children was found to show a similar response to the addition of excess pyridoxal phosphate. A method has been devised for the partial purification of human GPT (cytoplasmic) from liver. GPT 1 and GPT 2 have been purified, and very few significant differences were found amongst the physical and kinetic parameters tested.