Peroxynitrite mild nitration of albumin and LDL-albumin complex naturally present in plasma and tyrosine nitration rate-albumin impairs LDL nitration.
In blood, peroxynitrite (ONOO- ) and CO2 react to form NO2* and CO3* through the short-lived adduct ONOOCO2-, leading to protein-bound tyrosine nitration. ONOO(-) -modified LDL is atherogenic. Oxidatively modified LDL generally appears in the vessel wall surrounded by antioxidants. Human serum albumin (HSA) is one of them, partly associated to LDL as a LDL-albumin complex (LAC). The purpose was to study the effect of a mild nitration on LAC and whether albumin may interfere with LDL nitration. To do so, SIN-1 was used as ONOO- generator in the presence or absence of 25 mM HCO3-. The human serum albumin (HSA)-bound tyrosine nitration rate was found to be 4.4 x 10(-3) mol/mol in the presence of HCO3-. HSA decreased the LAC-tyrosine nitration rate from 2.5 x 10(-3) to 0.6 x 10(-3) mol/mol. It was concluded that HSA impaired the apoB-bound tyrosine nitration. These findings raise the question of the patho-physiological significance of these nitrations and their interactions which may potentially prevent both atheromatous plaque formation and endothelium dysfunction in particular and appear to be beneficial in terms of atherogenic risk.
Torres-Rasgado
Enrique
E
EA 2993 Nutrition Humaine et Athérogénèse, Faculté de Médecine, Institut de Biologie, Montpellier, France.
Fouret
Gilles
G
Carbonneau
Marie-Annette
MA
Leger
Claude-Louis
CL
D000975:Antioxidants / Q000378:metabolism*; D050197:Atherosclerosis / Q000209:etiology; D006801:Humans; D008077:Lipoproteins, LDL / Q000097:blood / Q000378:metabolism*; D008981:Molsidomine / Q000031:analogs & derivatives / Q000737:chemistry; D020030:Nitric Oxide Donors / Q000737:chemistry; D009585:Nitrogen Dioxide / Q000378:metabolism; D010084:Oxidation-Reduction; D030421:Peroxynitrous Acid / Q000097:blood / Q000378:metabolism*; D012709:Serum Albumin / Q000032:analysis / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism*
D000975:Antioxidants; D008077:Lipoproteins, LDL; D020030:Nitric Oxide Donors; D012709:Serum Albumin; D030421:Peroxynitrous Acid; D014443:Tyrosine; C002385:linsidomine; D008981:Molsidomine; D009585:Nitrogen Dioxide