RESUMO
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.
Assuntos
Metabolismo dos Carboidratos , Peptidil Dipeptidase A/metabolismo , Animais , Sítios de Ligação , Configuração de Carboidratos , Bovinos , Dimerização , Galactose/química , Humanos , Monossacarídeos/metabolismo , Ácido N-Acetilneuramínico/química , Peptidil Dipeptidase A/química , Conformação Proteica , Estrutura Terciária de Proteína , UltracentrifugaçãoRESUMO
Solid-phase enzyme immunoassay (EIA) was developed for detecting natural antibodies to angiotensine-converting enzyme (ACE). Optimal conditions for detecting natural anti-ACE by EIA in the sera of donors and patients with disorders of arterial pressure are selected. The findings indicate that the level of natural anti-ACE is normally constant, while in the patients it is increased in 50% cases.