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Analysis of active renin heterogeneity.
1Department of Medicine, Hennepin County Medical Center, University of Minnesota, Minneapolis 55415.
Summary
Renin heterogeneity arises from variations in its carbohydrate structures. Modifying these structures or removing carbohydrates shifts renin forms, but does not affect inhibitor binding to the active enzyme.
Area of Science:
- Biochemistry
- Enzymology
- Glycobiology
Background:
- Active renin exhibits heterogeneity, separable into multiple forms via isoelectric focusing.
- This heterogeneity is hypothesized to stem from variations in glycosylation patterns.
Purpose of the Study:
- To investigate the relationship between active renin's isoelectric heterogeneity and its oligosaccharide composition or attachment.
- To determine if renin heterogeneity impacts the efficacy of renin inhibitors.
Main Methods:
- Tunicamycin treatment of rat renal cortical slices to alter glycosylation.
- Endoglycosidase F treatment of human recombinant renin to remove carbohydrates.
- Inhibition assays using two distinct renin inhibitors on heterogeneous renin forms.
Main Results:
- Tunicamycin treatment increased the proportion of basic renin forms secreted by renal slices.
- Endoglycosidase F treatment shifted human recombinant renin towards more basic forms.
- Both tunicamycin and endoglycosidase F treatments indicated that carbohydrate attachment influences renin's charge heterogeneity.
- All heterogeneous renin forms were similarly inhibited by the tested renin inhibitors.
Conclusions:
- Renin's isoelectric heterogeneity is partly attributed to differences in carbohydrate moiety attachment.
- Renin heterogeneity does not impede the access of direct renin inhibitors to the enzyme's active site.