Glutamic dehydrogenase and aspartic and alanine aminotransferase activities in chick embryo liver

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Abstract
Concurrent assays for glutamic dehydrogenase (GDH), aspartic aminotransferase (AspAT), and alanine aminotransferase (AlaAT) activities were performed on water-ex-tractable and dtgitonin-extractable fractions of mitochondria isolated from the liver of chick embryos from the 8th day after fertilization to hatching, and from the liver of chicks during the first 3 weeks of neonatal life. For each of the enzyme activities, the 2 sequential mlto-chondrlal extracts exhibited the same pattern of change during development. AspAT activity reached a transient peak in early embryonic life when AlaAt and GDH activities were relatively low. This was followed by a period when AspAT activity decreased and GDH activity rose significantly to a plateau maintained until hatching. During the 1st day of neonatal life, GDH activity decreased sharply while the aminotransferase activities rose to sustained high values in the 1st week after hatching. These changes were not related to alterations in the total N2 content of these extracts. In the sucrose supernatant material from which the mitochondria had been isolated, only AspAT activity was demonstrable at pH 7.6; It remained unchanged throughout development.