Conformational aspects of angiotensinogen analogues with renin inhibitory activity.

Linear and cyclic peptides containing the His6-Pro7-Phe8-His9 sequence of renin's substrate (angiotensinogen) have been shown to be effective competitive inhibitors of the enzyme. Calculations and comparison of low energy structures for these peptides give support to the existence of a beta-turn-like structure involving the His-Pro-Phe-His region of the renin substrate and of the competitive inhibitors containing that sequence. This structure may be regarded as a possible "inhibition conformation", occurring in the process of binding to renin.