New feature of angiotensin‐converting enzyme: carbohydrate‐recognizing domain

Abstract

Self carbohydrate-mediated dimerization of glycoprotein angiotensin-converting enzyme (ACE) was demonstrated. The dimerization was studied in the reverse micelle experimental system as a model of biomembrane situation. Asialo-ACE or agalacto-ACE was able to form a dimer, whereas deglycosylated ACE and sequentially desialylated and degalactosylated ACE failed to dimerize. ACE-ACE interaction was competitively inhibited by Neu5Ac- or Gal-terminated saccharides. The results have allowed us to propose the existence of carbohydrate-recognizing domain (CRD) on ACE molecule. The structural requirements of this CRD were estimated based on the ability of saccharides to inhibit ACE dimerization. The most effective monosaccharides with equal inhibition potencies were shown to be galactose (as GalbetaOMe) and N-acetylneuraminic acid (as Neu5AcalphaOMe). Among oligosaccharides, the most effective ones were found to be 3'SiaLac and, especially, the whole pool of ACE oligosaccharide chains and biantennae complex oligosaccharide chains of other glycoproteins. Bovine and human ACEs were shown to be similar in terms of recognition of carbohydrates.

Investigation into the Mechanism of Homo- and Heterodimerization of Angiotensin-Converting Enzyme

“…Our observation of sACE dimerization in mammalian cells confirms previous studies that showed sACE dimerization in synthetic biomembranes, in crosslinking investigations, and in a Saccharomyces cerevisiae split-ubiquitin assay (Kost et al, 2000(Kost et al, , 2003Kohlstedt et al, 2006). However, to our knowledge, this is the first time that tACE dimerization has been described (Fig.…”

“…Previously, different interactions were proposed to be involved in dimerization. Dimerization of human sACE in reverse micelles was inhibited in the presence of galactose and it was suggested that a carbohydrate recognition domain in the N domain of sACE (Ndom) mediates dimerization (Kost et al, 2000). Alternatively, sACE active site mutants overexpressed in porcine aortic endothelial cells showed that a catalytically active C domain was required for dimerization and initiation of signaling (Kohlstedt et al, 2006).…”

Epitope-specific antibody-induced cleavage of angiotensin-converting enzyme from the cell surface

“…The fact that mAb 3G8 inhibited proteolytic cleavage of ACE from the cell surface is especially interesting. Recently it was shown that somatic ACE can form dimers in artificial membrane preparations (reverse micelles) and this process was inhibited effectively by several carbohydrates, including galactose [37]. We have found that, among our set of anti-ACE antibodies, only two mAbs, which are directed to overlapping but not identical epitopes, 3G8 and 9B9 [20], inhibited dimer formation in micelles.…”

Temperature‐induced selective death of the C‐domain within angiotensin‐converting enzyme molecule

“…Soluble forms of somatic and testicular ACEs were isolated from bovine lung and bovine testicles, respectively, by Triton X‐100 extraction and were further purified by lisinopril affinity chromatography as described in [12]. Membrane form of somatic ACE was isolated from bovine lung by Triton X‐100 extraction in the presence of 1 mM EDTA as described in [13]; the enzyme was purified by hydrophobic and affinity chromatography according to [14].…”