N-glycosylation of forms of angiotensin converting enzyme from four mammalian species.

To help clarify bases for the molecular weight and surface charge heterogeneities of forms of somatic angiotensin converting enzyme (ACE), we examined for differences in N-glycosylation. ACE preparations purified from human, guinea pig, rat and rabbit tissues were found to be heterogeneous in terms of numbers of N-glycosylated sites (7-8 sites per molecule of ACE) and in types of structures of oligosaccharides used for glycosylation (complex versus high mannose oligosaccharide contents). Our findings, taken with reports of potential N-glycosylation sites and amino acid sequencing data, indicate that ACE forms can differ in terms of degrees of glycosylation, sites of glycosylation and structures of attached oligosaccharide units.