Abstract
Oxidative modification of low-density lipoprotein (LDL) has been implicated in foam-cell formation at all stages of atherosclerosis. Since transition metals and mammalian 15-lipoxygenases are capable of oxidizing LDL to its atherogenic form, a concerted action of these two catalysts in atherogenesis has been suggested. Cu2+-catalysed LDL oxidation is characterized by a kinetic lag period in which the lipophilic antioxidants are decomposed and by a complex mixture of unspecific oxidation products. We investigated the kinetics of the 15-lipoxygenase-catalysed oxygenation of LDL and found that the enzyme is capable of oxidizing LDL in the presence of the endogenous lipophilic antioxidants. In contrast with the Cu2+-catalysed reaction, no kinetic lag phase was detected. The pattern of products formed during short-term incubations was highly specific, with cholesterol-esterified (13S)-hydroperoxy-(9Z,11E)-octadecadinoic acid being the major product. However, after long-term incubations the product pattern was less specific. Preincubation with 15-lipoxygenase rendered human LDL more susceptible to Cu2+-catalysed oxidation as indicated by a dramatic shortening of the lag period. Addition of Cu2+ to lipoxygenase-treated LDL led to a steep decline in its antioxidant content and to a greatly reduced lag period. Interestingly, if normalized to a comparable hydroperoxide content, autoxidation and addition of exogenous hydroperoxy fatty acids both failed to overcome the lag period. The local peroxide concentrations in various LDL subcompartments will be discussed as a possible reason for this unexpected behaviour.
Full Text
The Full Text of this article is available as a PDF (698.1 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Belkner J., Wiesner R., Rathman J., Barnett J., Sigal E., Kühn H. Oxygenation of lipoproteins by mammalian lipoxygenases. Eur J Biochem. 1993 Apr 1;213(1):251–261. doi: 10.1111/j.1432-1033.1993.tb17755.x. [DOI] [PubMed] [Google Scholar]
- Esterbauer H., Gebicki J., Puhl H., Jürgens G. The role of lipid peroxidation and antioxidants in oxidative modification of LDL. Free Radic Biol Med. 1992 Oct;13(4):341–390. doi: 10.1016/0891-5849(92)90181-f. [DOI] [PubMed] [Google Scholar]
- Esterbauer H., Striegl G., Puhl H., Rotheneder M. Continuous monitoring of in vitro oxidation of human low density lipoprotein. Free Radic Res Commun. 1989;6(1):67–75. doi: 10.3109/10715768909073429. [DOI] [PubMed] [Google Scholar]
- Folcik V. A., Nivar-Aristy R. A., Krajewski L. P., Cathcart M. K. Lipoxygenase contributes to the oxidation of lipids in human atherosclerotic plaques. J Clin Invest. 1995 Jul;96(1):504–510. doi: 10.1172/JCI118062. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gan Q. F., Witkop G. L., Sloane D. L., Straub K. M., Sigal E. Identification of a specific methionine in mammalian 15-lipoxygenase which is oxygenated by the enzyme product 13-HPODE: dissociation of sulfoxide formation from self-inactivation. Biochemistry. 1995 May 30;34(21):7069–7079. doi: 10.1021/bi00021a019. [DOI] [PubMed] [Google Scholar]
- Garssen G. J., Vliegenthart J. F., Boldingh J. The origin and structures of dimeric fatty acids from the anaerobic reaction between soya-bean lipoxygenase, linoleic acid and its hydroperoxide. Biochem J. 1972 Nov;130(2):435–442. doi: 10.1042/bj1300435. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Henriksen T., Mahoney E. M., Steinberg D. Enhanced macrophage degradation of low density lipoprotein previously incubated with cultured endothelial cells: recognition by receptors for acetylated low density lipoproteins. Proc Natl Acad Sci U S A. 1981 Oct;78(10):6499–6503. doi: 10.1073/pnas.78.10.6499. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Holvoet P., Collen D. Oxidized lipoproteins in atherosclerosis and thrombosis. FASEB J. 1994 Dec;8(15):1279–1284. doi: 10.1096/fasebj.8.15.8001740. [DOI] [PubMed] [Google Scholar]
- Holvoet P., Perez G., Bernar H., Brouwers E., Vanloo B., Rosseneu M., Collen D. Stimulation with a monoclonal antibody (mAb4E4) of scavenger receptor-mediated uptake of chemically modified low density lipoproteins by THP-1-derived macrophages enhances foam cell generation. J Clin Invest. 1994 Jan;93(1):89–98. doi: 10.1172/JCI116988. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kühn H., Belkner J., Suzuki H., Yamamoto S. Oxidative modification of human lipoproteins by lipoxygenases of different positional specificities. J Lipid Res. 1994 Oct;35(10):1749–1759. [PubMed] [Google Scholar]
- Kühn H., Belkner J., Wiesner R., Schewe T., Lankin V. Z., Tikhaze A. K. Structure elucidation of oxygenated lipids in human atherosclerotic lesions. Eicosanoids. 1992;5(1):17–22. [PubMed] [Google Scholar]
- Kühn H., Wiesner R., Rathmann J., Schewe T. Formation of ketodienoic fatty acids by the pure pea lipoxygenase-1. Eicosanoids. 1991;4(1):9–14. [PubMed] [Google Scholar]
- Ludwig P., Holzhütter H. G., Colosimo A., Silvestrini M. C., Schewe T., Rapoport S. M. A kinetic model for lipoxygenases based on experimental data with the lipoxygenase of reticulocytes. Eur J Biochem. 1987 Oct 15;168(2):325–337. doi: 10.1111/j.1432-1033.1987.tb13424.x. [DOI] [PubMed] [Google Scholar]
- Morton R. E., Steinbrunner J. V. Concentration of neutral lipids in the phospholipid surface of substrate particles determines lipid transfer protein activity. J Lipid Res. 1990 Sep;31(9):1559–1567. [PubMed] [Google Scholar]
- O'Leary V. J., Darley-Usmar V. M., Russell L. J., Stone D. Pro-oxidant effects of lipoxygenase-derived peroxides on the copper-initiated oxidation of low-density lipoprotein. Biochem J. 1992 Mar 15;282(Pt 3):631–634. doi: 10.1042/bj2820631. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ross R. The pathogenesis of atherosclerosis: a perspective for the 1990s. Nature. 1993 Apr 29;362(6423):801–809. doi: 10.1038/362801a0. [DOI] [PubMed] [Google Scholar]
- Sattler W., Mohr D., Stocker R. Rapid isolation of lipoproteins and assessment of their peroxidation by high-performance liquid chromatography postcolumn chemiluminescence. Methods Enzymol. 1994;233:469–489. doi: 10.1016/s0076-6879(94)33053-0. [DOI] [PubMed] [Google Scholar]
- Schewe T., Rapoport S. M., Kühn H. Enzymology and physiology of reticulocyte lipoxygenase: comparison with other lipoxygenases. Adv Enzymol Relat Areas Mol Biol. 1986;58:191–272. doi: 10.1002/9780470123041.ch6. [DOI] [PubMed] [Google Scholar]
- Sparrow C. P., Parthasarathy S., Steinberg D. Enzymatic modification of low density lipoprotein by purified lipoxygenase plus phospholipase A2 mimics cell-mediated oxidative modification. J Lipid Res. 1988 Jun;29(6):745–753. [PubMed] [Google Scholar]
- Steinberg D., Witztum J. L. Lipoproteins and atherogenesis. Current concepts. JAMA. 1990 Dec 19;264(23):3047–3052. [PubMed] [Google Scholar]
- Takano T., Mineo C. Atherosclerosis and molecular pathology: mechanisms of cholesteryl ester accumulation in foam cells and extracellular space of atherosclerotic lesions. J Pharmacobiodyn. 1990 Jul;13(7):385–413. doi: 10.1248/bpb1978.13.385. [DOI] [PubMed] [Google Scholar]
- Veldink G. A., Vliegenthart J. F., Boldingh J. Plant lipoxygenases. Prog Chem Fats Other Lipids. 1977;15(2):131–166. doi: 10.1016/0079-6832(77)90014-3. [DOI] [PubMed] [Google Scholar]
- Vuilleumier J. P., Keller H. E., Gysel D., Hunziker F. Clinical chemical methods for the routine assessment of the vitamin status in human populations. Part I: The fat-soluble vitamins A and E, and beta-carotene. Int J Vitam Nutr Res. 1983;53(3):265–272. [PubMed] [Google Scholar]
- Yamamoto Y., Brodsky M. H., Baker J. C., Ames B. N. Detection and characterization of lipid hydroperoxides at picomole levels by high-performance liquid chromatography. Anal Biochem. 1987 Jan;160(1):7–13. doi: 10.1016/0003-2697(87)90606-3. [DOI] [PubMed] [Google Scholar]