title: Proteomic analysis of electronegative low-density lipoprotein.
abstract: Low density lipoprotein is a heterogeneous group of lipoproteins that differs in lipid and protein composition. One copy of apolipoprotein (apo)B accounts for over 95% of the LDL protein, but the presence of minor proteins could disturb its biological behavior. Our aim was to study the content of minor proteins in LDL subfractions separated by anion exchange chromatography. Electropositive LDL [LDL(+)] is the native form, whereas electronegative LDL [LDL⁻] is a minor atherogenic fraction present in blood. LC-ESI MS/MS analysis of both LDL fractions identified up to 28 different proteins. Of these, 13 proteins, including apoB, were detected in all the analyzed samples. LDL⁻ showed a higher content of most minor proteins. Statistical analysis of proteomic data indicated that the content of apoE, apoA-I, apoC-III, apoA-II, apoD, apoF, and apoJ was higher in LDL⁻ than in LDL(+). Immunoturbidimetry, ELISA, or Western blot analysis confirmed these differences. ApoJ and apoF presented the highest difference between LDL(+) and LDL⁻ (>15-fold). In summary, the increased content of several apolipoproteins, and specifically of apoF and apoJ, could be related to the physicochemical characteristics of LDL⁻, such as apoB misfolding, aggregation, and abnormal lipid composition.
authors.affiliation: Servei de Bioquímica, Institut de Recerca, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Bancells
authors.forename: Francesc
authors.initials: F
authors.lastname: Canals
authors.forename: Sònia
authors.initials: S
authors.lastname: Benítez
authors.forename: Nuria
authors.initials: N
authors.lastname: Colomé
authors.forename: Josep
authors.initials: J
authors.lastname: Julve
authors.forename: Jordi
authors.initials: J
authors.lastname: Ordóñez-Llanos
authors.forename: José Luis
authors.initials: JL
authors.lastname: Sánchez-Quesada
mesh_terms: D001053:Apolipoproteins / Q000032:analysis* / Q000097:blood / Q000235:genetics / Q000378:metabolism; D001161:Arteriosclerosis / Q000378:metabolism* / Q000473:pathology; D015153:Blotting, Western; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D008077:Lipoproteins, LDL / Q000032:analysis* / Q000097:blood / Q000235:genetics / Q000378:metabolism; D009391:Nephelometry and Turbidimetry; D040901:Proteomics / Q000379:methods*
chemical_list: D001053:Apolipoproteins; D008077:Lipoproteins, LDL