Computer graphics modelling and the specificity of renins.

Mouse submaxillary, mouse kidney and human renins have been modelled using the three-dimensional structure of the homologous endothiapepsin, which has been defined by high-resolution X-ray analysis, and the amino acid sequences derived from protein, complementary DNA or gene sequencing. These computer graphics studies have shown that all renins can adopt three-dimensional structures similar to those of other aspartic proteinases with small insertions and deletions at the surface and often at beta-turns. The catalytically essential aspartates lie at the centre of a deep and extended cleft, and differences in the subsites, especially at S3' have been correlated with the known specificities of the renins. The models have shown that various residues on the surfaces of the renins adjacent to the active site cleft may play a part in recognizing and binding angiotensinogen. Reasons for a neutral pH optima have also been suggested.