Serum N-acetyl-ß-D-glucosaminidase (NAG) activity in streptozotocin-induced
diabetic rats was significantly increased. There was neither a difference in (a) total NAG
activity in kidney and liver, nor (b) in optimal pH of NAG in serum, kidney and liver between
diabetic and control rats. The ratio of the thermounstable fraction of NAG increased in
diabetic kidney and liver, while there was no difference in thermostability of serum NAG
between diabetic and control rats. Isoelectricfocusing of diabetic serum NAG indicated an
increase in the neutral form. That of kidney and liver NAG indicated an increase in the acid
form. These results may suggest that NAG clearance from the serum is decreased in the
diabetic state.