Angiotensinase activity in red blood cell membranes and intact adrenal cells

The present study was undertaken to characterize angiotensinase activity in human red blood cells (RBCs), RBC ghosts and rabbit adrenal cells. It was found, by the use of paper chromatography, that each of these preparations possess enzymes capable of converting angiotensin II to its heptapeptide derivative, [des=Asp1] angiotensin II (angiotensin III). Further characterization of these enzymes by the use of a chromogenic assay indicates that although intact RBCs do not split sarcosine-beta-naphthylamide, RBC ghosts do. Intact rabbit adrenal cells from the zona glomerulosa, however, do show activity against sarcosine-beta-naphthylamide. This is interpreted to indicate the presence of non-specific angiotensinases on the inside of the RBC membrane and the outside of the adrenal cell membrane.