Carbamylation of erythrocyte membrane aminophospholipids: an in vitro and in vivo study.
OBJECTIVE
To study the binding of cyanate to erythrocyte membrane aminophospholipids in vitro, and to investigate whether carbamylated aminophospholipids can be detected in the plasma membrane of native erythrocytes.


METHODS
For in vitro studies, the lipid components of 14C-carbamylated erythrocyte membranes were resolved by thin-layer chromatography (TLC). The covalent incorporation of cyanate was visualized by autoradiography and quantitated by phosphorus analysis. For the in vivo studies, phospholipid headgroups were enzymatically hydrolyzed by phospholipase D and subsequently reacted with diacetyl monoxime.


RESULTS
Both phosphatidylethanolamine (PE) and phosphatidylserine (PS) were covalently modified by [14C] cyanate; incorporating 15.76 +/- 0.09 and 13.34 +/- 0.81 mol%, respectively, following a 15-h incubation. Carbamylated PE (carb-PE) was resolved with PE by TLC in a solvent system consisting of chloroform/methanol/ammonia (65/35/5, v/v/v). Treatment of native erythrocyte membrane lipid micelles with phospholipase D, followed by reaction with diacetyl monoxime, suggests the presence of intrinsic carb-PE (2.85 +/- 0.65 percent of the total PE).


CONCLUSIONS
Carbamylation of erythrocyte aminophospholipid may be involved in some of the hematological consequences of uremia on the erythrocyte.
Trepanier
D J
DJ
Department of Chemistry and Biochemistry, University of Windsor, Ontario, Canada.
Thibert
R J
RJ
D001345:Autoradiography; D002221:Carbamyl Phosphate / Q000378:metabolism*; D002855:Chromatography, Thin Layer; D003485:Cyanates / Q000378:metabolism; D004910:Erythrocyte Membrane / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008823:Micelles; D008956:Models, Chemical; D017830:Octoxynol; D010714:Phosphatidylethanolamines / Q000378:metabolism*; D010718:Phosphatidylserines / Q000378:metabolism*; D010739:Phospholipase D / Q000378:metabolism; D013054:Spectrophotometry, Atomic
D003485:Cyanates; D008823:Micelles; D010714:Phosphatidylethanolamines; D010718:Phosphatidylserines; D002221:Carbamyl Phosphate; D017830:Octoxynol; D010739:Phospholipase D