Low molecular weight renin as a storage form in renin granules of the dog

The molecular weight of renin extracted from isolated renin granules of the dog was estimated by gel filtration, using tetradecapeptide as substrate, and was approximately 43,000 daltons. Neither big renin nor big big renin was demonstrable. On the other hand, crude extract of kidney cortex showed angiotensin I generating enzymes other than 43,000 dalton form of renin, whose molecular weight were over 100,000 and around 70,000 daltons. They seemed nonspecific proteases, since they hydrolyzed tetradecapeptide but not plasma angiotensinogen. Therefore renin is stored in the renin granules as a low molecular weight form.