Partial purification and chromatographic properties of inactive renin from human amniotic fluid

Inactive renin from human amniotic fluid was partially purified using gel filtration and several types of affinity chromatography. The Chromatographie steps employed resulted in a 62-fold purification of inactive renin with an overall yield of 11 per cent. Inactive renin was retained on an Affi-Gel Blue column and could be eluted with 1.4 M NaCl. Chromatography on a concanavalin A-agarose affinity column yielded two fractions. The non-retained fraction contained the inactive renin while the retained fraction contained cathepsin D. Acid or pepsin activation of the non-retained inactive renin, followed by concanavalin A chromatography, resulted in the retention of 33 per cent of the applied renin activity. Inactive renin was also not retained on a pepstatin affinity column. However, after the activation of the inactive renin with pepsin, the enzymatic activity was bound to the pepstatin column. Gel filtration on Sephacryl S-200 indicated that inactive renin had a molecular weight of 39,000. No change in molecular weight was observed after activation with pepsin.