TY - JOUR
T1 - Apolipoprotein B carbonyl formation is enhanced by lipid peroxidation during copper-mediated oxidation of human low-density lipoproteins
AU - Yan, Liang Jun
AU - Lodge, John K.
AU - Traber, Maret G.
AU - Packer, Lester
N1 - Funding Information:
We thank Dr Hong-Duk Youn for assistance with SDS±PAGE analysis. Research for this project was funded by the Tobacco-Related Disease Research Program of the University of California, Grant No. 4RT0065.
PY - 1997/3/1
Y1 - 1997/3/1
N2 - To determine whether lipid peroxidation is required for apolipoprotein B (apoB) carbonyl formation of human low-density lipoproteins (LDL) during copper-mediated oxidation, we investigated oxidation of native and probucol- preloaded LDL by measuring thiobarbituric acid-reactive substances (TBARS) and apoB carbonyls. Probucol was used because it is known to inhibit lipid peroxidation, but not protein modification. During copper-mediated oxidation, apoB carbonyls formed in a time-dependent manner; high copper concentrations (≤30 μM) resulted in saturation of apoB carbonyl content. ApoB carbonyl formation and lipid peroxidation were linearly related during incubation of LDL with copper for 3 h. During Cu2+-mediated LDL oxidation of probucol- LDL, TBARS production was very low, nonetheless apoB carbonyls increased significantly, and vitamin E was depleted. Bovine serum albumin (fatty acid free; BSA) oxidation in the presence of trace amounts of LDL, linoleic acid, or tert-butyl hydroperoxide was used to further understand the role of lipid peroxidation in apoB carbonyl formation. Protein carbonyl formation during BSA incubation with copper (either Cu+ or Cu2+) was trivial; however, further addition of linoleic acid (1:1, m/m), trace amounts of LDL (10 μg/ml), or tert-butyl hydroperoxide (1:1, m/m) markedly increased protein carbonyl formation. These results demonstrate that lipid peroxidation enhances copper-mediated carbonyl formation and suggest that copper ions react with LDL lipid hydroperoxides producing the necessary reactive species.
AB - To determine whether lipid peroxidation is required for apolipoprotein B (apoB) carbonyl formation of human low-density lipoproteins (LDL) during copper-mediated oxidation, we investigated oxidation of native and probucol- preloaded LDL by measuring thiobarbituric acid-reactive substances (TBARS) and apoB carbonyls. Probucol was used because it is known to inhibit lipid peroxidation, but not protein modification. During copper-mediated oxidation, apoB carbonyls formed in a time-dependent manner; high copper concentrations (≤30 μM) resulted in saturation of apoB carbonyl content. ApoB carbonyl formation and lipid peroxidation were linearly related during incubation of LDL with copper for 3 h. During Cu2+-mediated LDL oxidation of probucol- LDL, TBARS production was very low, nonetheless apoB carbonyls increased significantly, and vitamin E was depleted. Bovine serum albumin (fatty acid free; BSA) oxidation in the presence of trace amounts of LDL, linoleic acid, or tert-butyl hydroperoxide was used to further understand the role of lipid peroxidation in apoB carbonyl formation. Protein carbonyl formation during BSA incubation with copper (either Cu+ or Cu2+) was trivial; however, further addition of linoleic acid (1:1, m/m), trace amounts of LDL (10 μg/ml), or tert-butyl hydroperoxide (1:1, m/m) markedly increased protein carbonyl formation. These results demonstrate that lipid peroxidation enhances copper-mediated carbonyl formation and suggest that copper ions react with LDL lipid hydroperoxides producing the necessary reactive species.
KW - apolipoprotein B
KW - copper
KW - low-density lipoproteins
KW - probucol-LDL
KW - protein carbonyls
KW - thiobarbituric acid-reactive substances
UR - http://www.scopus.com/inward/record.url?scp=0031104981&partnerID=8YFLogxK
U2 - 10.1006/abbi.1996.9867
DO - 10.1006/abbi.1996.9867
M3 - Article
C2 - 9056246
AN - SCOPUS:0031104981
VL - 339
SP - 165
EP - 171
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
SN - 0003-9861
IS - 1
ER -