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.
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Acknowledgements-This work was supported in part by a grant from the Kansas Heart Association. We wish to acknowledge the expert technical assistanceo f Mr. Greg Hanna and Mrs. Roselle Poisner.