Purification of hog renin by affinity chromatography using the synthetic competitive inhibitor (D-Leu6)octapeptide

The renin substrate analog His-Pro-Phe-His-Leu-D-Leu-Val-Tyr ([D-Leu6]-octapeptide) acts as a potent inhibitor of renin because of the D-amino acid substitution at the cleavage site. This inhibitor was coupled to CNBr-activated Sepharose 4B to yield a support for affinity chromatography. Hog renin with a specific activity of 1.2 Goldblatt units/mg was in one step purified 195-fold to a final specific activity of 234 Goldblatt units/mg. Application of a pH gradient from 5.0 to 7.5 to the support was found to be the most successful elution program, probably because the [D-Leu6]-octapeptide is not an inhibitor for renin at neutral pH.