A comparison of the cytosolic and mitochondrial forms of asparagine/glyoxylate aminotransferase.

Asparagine aminotransferase activity was measured in a variety of mouse tissues. The liver had the highest activity--nearly 20 times more than any of the other tissues tested. Hepatic asparagine aminotransferase was found to consist of cytosolic and mitochondrial forms. The mitochondrial form was found to be the predominant form in mouse tissue. Gel filtration chromatography indicated that the mouse enzyme forms have comparable molecular weights of approximately 70,000. While the substrate specificities of the two forms are very different, asparagine was the preferred amino donor for both forms. The relative contribution to the total activity of the hepatic enzyme forms varies with the animal source. Mouse had the highest level of enzyme activity of all animals tested. Ratios of the two enzyme forms also varied greatly not only with the animal source but also with the substrate used and the isolation conditions.