OBSERVATIONS CONCERNING THE PRESENCE OF ISOCITRIC DEHYDROGENASE IN MITOCHONDRIA

The intracellular distribution of rat and human liver isocitric dehydrogenase is essentially the same as that of mouse and rabbit liver. This enzyme is largely cytoplasmic but washing does not remove all of the activity from the mitochondria. A method is outlined using permeability considerations as a test of whether an enzyme is within the mitochondria or adsorbed thereon. This method, when applied to washed liver mitochondria, indicates that some isocitric dehydrogenase activity is within the liver mitochondria of rat and rabbit. The results were not conclusive with human liver.