Two peaks in pH dependence of renin-angiotensinogen reaction

The pH dependence of the reaction of purified recombinant human renin with purified recombinant sheep angiotensinogen was not a typical bell-shape but had two peaks, pH 6.4 and 8.9. The pH dependence of the reaction of human renin with human, hog, and rat angiotensinogens partially purified from plasma had a peak with a shoulder containing two peaks close together. These findings indicate that the reaction of renin with angiotensinogen involves at least two amino acid residues other than the two aspartic acid residues known to be involved and occurs at acidic pH and basic pH by two different pairs of these amino acid residues.