[Activity of DNAase I inhibitor in subcellular fractions of rat tissues].

The inhibitory activity in the mitochondrial and postmitochondrial fractions of the liver, spleen and thymus of albino rats was studied with respect to pancreatic DNase I. It is shown to be due to the presence of thermolabile substances of protein nature (natural inhibitors of DNase I) in the subcellular fractions of the organs under study. A higher inhibitory activity is detected in the postmitochondrial fraction of all the tissues under investigation. The lowest inhibitory activity is found in the mitochondrial and postmitochondrial fractions of the liver. The data of a simultaneous study of changes in the activity of tissue DNase and inhibitory activity in the subcellular fractions give reasons to suppose the presence of the nuclease-inhibitory complex in the tissues.