Glycation and inactivation of aspartate aminotransferase in diabetic rat tissues

Glycated cytosolic aspartate aminotransferase was detected in the liver and kidney of streptozotocin diabetic rats using a boronate affinity column for adjacent cis-hydroxyl groups and an immunoblotting technique. The enzymatic activity and amount of immunoreactive substance were determined in the liver, kidney, and erythrocytes of diabetic and control rats. The ratio of enzymatic activity to the amount of enzyme was lower in diabetic rat tissue than in that in the control rats. It has been suggested that there is an inactive aspartate aminotransferase molecule in the tissues of diabetic rats. We therefore suggest that the cytosolic aspartate aminotransferase was inactivated in the diabetic rat tissues by a glycation reaction, accompanied by an impairment in glucose utilization.