Formation of lipid-protein adducts in low-density lipoprotein by fluxes of peroxynitrite and its inhibition by nitric oxide.
Peroxynitrite (PN), the product of the diffusion-limited reaction between nitric oxide (*NO) and superoxide (O*-(2)), represents a relevant mediator of oxidative modifications in low-density lipoprotein (LDL). This work shows for the first time the simultaneous action of low-controlled fluxes of PN and *NO on LDL oxidation in terms of lipid and protein modifications as well as oxidized lipid-protein adduct formation. Fluxes of PN (e.g., 1 microM min(-1)) initiated lipid oxidation in LDL as measured by conjugated dienes and cholesteryl ester hydroperoxides formation. Oxidized-LDL exhibited a characteristic fluorescent emission spectra (lambda(exc) = 365 nm, lambda(max) = 417 nm) in parallel with changes in both the free amino groups content and the relative electrophoretic mobility of the particle. Physiologically relevant fluxes of *NO (80-300 nM min(-1)) potently inhibited these PN-dependent oxidative processes. These results are consistent with PN-induced adduct formation between lipid oxidation products and free amino groups of LDL in a process prevented by the simultaneous presence of *NO. The balance between rates of PN and *NO production in the vascular wall will critically determine the final extent of LDL oxidative modifications leading or not to scavenger receptor-mediated LDL uptake and foam cell formation.
Trostchansky
A
A
Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay.
Batthyány
C
C
Botti
H
H
Radi
R
R
Denicola
A
A
Rubbo
H
H
D006801:Humans; D050356:Lipid Metabolism; D008077:Lipoproteins, LDL / Q000378:metabolism*; D008081:Liposomes / Q000378:metabolism; D008956:Models, Chemical; D009569:Nitric Oxide / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D030421:Peroxynitrous Acid / Q000378:metabolism*; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D013997:Time Factors
D008077:Lipoproteins, LDL; D008081:Liposomes; D011506:Proteins; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; D010100:Oxygen