Separation of isorenin activity from nerve growth factor (NGF) activity in mouse submaxillary gland extracts

Submaxillary glands of adult male mice contain large amounts of isorenin and of nerve growth factor (NGF). Since the NGF preparations available so far contain isorenin activity, we tried to separate the two biological activities. By means of Sephadex fractionation and chromatographic methods an NGF preparation free from isorenin activity and an isorenin preparation free from NGF activity were obtained. On the basis of acrylamide-gel electrophoresis a molecular weight of between 35,000 and 40,000 was calculated for isorenin, which is similar to that of kidney renin from various species. The close association of isorenin and NGF and their dependence on the male hormone suggest that the two factors are produced in the same cells, probably located in the tubules.