Presence of CuZn superoxide dismutase in human serum lipoproteins.
It has previously been demonstrated that CuZn-superoxide dismutase (SOD) is secreted by several human cell lines. This suggests that the circulating enzyme derives from both hemolysis and peripheral tissues as a result of cellular secretion. In the present report, we evaluated the presence of CuZn-SOD in human serum lipoproteins by both enzyme-linked immunosorbent assay and Western blot analysis of immunoprecipitated lipoprotein samples. The distribution of CuZn-SOD activity among the different lipoprotein fractions was also determined by the xanthine/xanthine oxidase method. The results demonstrated that CuZn-SOD is noticeably present in serum lipoproteins and mainly in low and high density lipoproteins (LDL and HDL). Moreover, experiments performed by incubating CuZn-SOD with a lipid emulsion and subsequent separation of the lipid fraction by ultracentrifugation showed that this enzyme associates in a saturable manner with lipids. The CuZn-SOD bound to LDL and HDL could exert a physiological protective role against oxidative damage of these lipoprotein classes that carry out a crucial role in the cholesterol transport.
Mondola
P
P
Dipartimento di Neuroscienze e della Comunicazione Interumana-Sez. Fisiologia, Via S. Pansini 5, 80131, Naples, Italy. mondola@unina.it
Bifulco
M
M
Serù
R
R
Annella
T
T
Ciriolo
M R
MR
Santillo
M
M
D000328:Adult; D001692:Biological Transport; D015153:Blotting, Western; D002352:Carrier Proteins / Q000097:blood / Q000737:chemistry / Q000145:classification / Q000378:metabolism; D004655:Emulsions; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008074:Lipoproteins / Q000097:blood* / Q000737:chemistry / Q000145:classification / Q000378:metabolism*; D008075:Lipoproteins, HDL / Q000097:blood / Q000737:chemistry / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000097:blood / Q000737:chemistry / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011485:Protein Binding; D013482:Superoxide Dismutase / Q000032:analysis / Q000097:blood* / Q000378:metabolism*; D014461:Ultracentrifugation
D002352:Carrier Proteins; D004655:Emulsions; D008074:Lipoproteins; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D013482:Superoxide Dismutase