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

Self carbohydrate-mediated dimerization of glycoprotein angiotensin-convert ing enzyme (ACE) was demonstrated. The dimerization was studied in the reve rse micelle experimental system as a model of biomembrane situation. Asialo -ACE or agalacto-ACE was able to form a dimer, whereas deglycosylated ACE a nd sequentially desialylated and degalactosylated ACE failed to dimerize, A CE-ACE interaction was competitively inhibited by Neu5Ac- or Gal-terminated saccharides, The results have allowed us to propose the existence of carbo hydrate-recognizing domain (CRD) on ACE molecule. The structural requiremen ts of this CRD were estimated based on the ability of saccharides to inhibi t ACE dimerization. The most effective monosaccharides with equal inhibitio n potencies were shown to be galactose (as Gal beta OMe) and N-acetylneuram inic acid (as Neu5Ac alpha OMe). Among oligosaccharides, the most effective ones were found to be 3'SiaLac and, especially, the whole pool of ACE olig osaccharide chains and biantennae complex oligosaccharide chains of other g lycoproteins, Bovine and human ACEs were shown to be similar in terms of re cognition of carbohydrates. Copyright (C) 2000 John Wiley & Sons, Ltd.