crystals of angiotensinogen and the complex of human angiotensinogen with de - glycosylated renin - asp292ala were grown at room temperature under conditions listed in supplementary table 1 . datasets were collected at 100k at the daresbury and diamond synchrotron light sources and processed with the ccp4 program suite . the structures of human , rat and mouse angiotensinogen were solved by molecular replacement in phaser27 , using an ensemble of distantly related serpins as the search model with additional phase information obtained from a gdcl3 derivative of human angitensinogen . the structure of the complex with renin was solved by molecular replacement using renin from pdb entry 2bks28 and its peptide complex from pdb entry 1smr7 . further details related to crystal structures and refinement , recombinant expression , thiol titration and nitrosylation and the assessment of sulphydryl blockage and oxidation , the determination of redox potentials , renin kinetics and the demonstration of reduced and oxidised forms of angiotensinogen , are given in methods .