Immunoelectrophoretic analysis of renal and intestinal brush border converting enzyme

Antibodies raised against purified hog renal or intestinal brush border protein or against purified hog kidney angiotensin I converting enzyme (ACE) were used to characterize renal and intestinal brush border ACE by techniques of differential solubilization, fused-rocket, line absorption and crossed-immunoelectrophoresis. Renal ACE is immunologically identical to intestinal ACE. ACE is present as a major intrinsic protein of renal brush border and a minor intrinsic protein of intestinal brush border. Renal and intestinal brush border ACE could be solubilized by detergent and/or papain. The electrophoretic mobilities of the papain-treated forms of ACE were greater than the detergent-treated forms. This increased mobility was associated with the removal of a small, non-antigenic component of the enzyme. Thus, like several other intrinsic brush border peptidases, ACE is bound to renal and intestinal brush border by a small hydrophobic anchor.