Biochemistry of Human Converting Enzyme

Abstract

Angiotensin converting enzyme (ACE, EC 3.4.15.1) was purified to homogeneity from human kidney and its specific antibody was raised in the rabbit. The antibody cross-reacted equally with human enzymes from kidney, lung, intestine, plasma and urine. Immunofluorescent and immunoelectron microscopic observation indicated that the enzyme was located on the plasma membrane and micropinocytic vesicles at the luminal site of vascular endothelium in the lung. It was also present on the brush border, intercellular and basal infolding membranes of proximal tubular epithelium, but was not detected on the distal tubular epithelium or vascular endothelium in the kidney. ACE was demonstrated immunocytologically in human alveolar macrophages and renal carcinoma tissues. The carcinoma tissue contained a possible isoenzyme of ACE differing in part immunologically from the enzyme of normal kidney.

Key Words:

• Angiotensin converting enzyme
• Kininase II
• Isoenzyme