Purification of high molecular weight forms of renin from hog kidney

To elucidate the possible regulatory function of high molecular weight renins in blood pressure control, studies were initiated to purify and characterize the high molecular weight enzyme. To avoid the destructive effect of acidification during affinity chromatographic elution, pepstatin-aminobutyl-agarose gel was used from which renin could be eluted at a neutral pH in 2 M urea. Three additional steps of conventional chromatography after the affinity technique produced two types of high molecular weight renins in electrophoretically homogeneous forms. Big renin with a molecular weight of 61,000 has a specific activity approximately 20% of the fully active small molecular weight renin (mol wt 40,000). Big big renins with molecular weights of 140,000 were discovered and purified in two homogeneous forms with specific activities less than 1% of the fully active renin. The possibility of zymogen-enzyme relationship involving the big big, the big, and the fully small molecular weight renins is discussed.