Homocysteine thiolactone is a cyclic thioester that is implicated in atherogenesis. This molecule will readily acylate primary amines, forming a homocystamide adduct, which contains a primary amine and a thiol. Here, we have characterized and evaluated the antioxidant potential of the homocystamide-low-density lipoprotein (LDL) adduct, a product of the acylation reaction between homocysteine thiolactone and LDL. Treatment of LDL with homocysteine thiolactone resulted in a time-dependent increase in LDL-bound thiol content that reached approximately 250 nmol thiol/mg LDL protein at 75 minutes. The increase in LDL thiol content was followed by aggregation of LDL after 75 minutes. The increase in LDL-bound thiols was reversible by treatment with the thiol blockersing spin label, methanethiosulfonate. As assessed by the electron spin resonance (ESR) spin labeling technique, the homocystamide adducts were predominately exposed to the aqueous phase of LDL, shown by the sharp ESR spectra that were greatly broadened by the hydrophillic paramagnetic relaxing agent, chromium oxalate. The relative electrophoretic mobility of the homocystamide-LDL adduct was increased with respect to native LDL. Primary amino group concentration of homocysteine thiolactone-treated LDL was not significantly different than native LDL (p < 0.05). The homocystamide-LDL adduct was resistant to Cu(2+)- and 2,2'-azobis (2-amidinopropane)- mediated oxidation (with respect to native LDL) as measured by the formation of thiobarbituric reactive substances and the depletion of vitamin E. Blocking thiols with N-ethylmaleamide prevented the antioxidant effect of the homocystamide-LDL adduct. The potential relationship between the homocystamide-LDL adduct and the development of atherosclerosis is discussed.?

Agency
National Institute of Health (NIH)
Institute
National Center for Research Resources (NCRR)
Type
Biotechnology Resource Grants (P41)
Project #
5P41RR001008-25
Application #
6307877
Study Section
Project Start
2000-03-01
Project End
2001-02-28
Budget Start
1998-10-01
Budget End
1999-09-30
Support Year
25
Fiscal Year
2000
Total Cost
$11,274
Indirect Cost
Name
Medical College of Wisconsin
Department
Type
DUNS #
937639060
City
Milwaukee
State
WI
Country
United States
Zip Code
53226
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Sheng, Zhi-Guo; Huang, Wei; Liu, Yu-Xiang et al. (2013) Ofloxacin induces apoptosis via ?1 integrin-EGFR-Rac1-Nox2 pathway in microencapsulated chondrocytes. Toxicol Appl Pharmacol 267:74-87
Sheng, Zhi-Guo; Huang, Wei; Liu, Yu-Xiang et al. (2013) Bisphenol A at a low concentration boosts mouse spermatogonial cell proliferation by inducing the G protein-coupled receptor 30 expression. Toxicol Appl Pharmacol 267:88-94
Liddle, Brendan J; Wanniarachchi, Sarath; Hewage, Jeewantha S et al. (2012) Electronic communication across diamagnetic metal bridges: a homoleptic gallium(III) complex of a redox-active diarylamido-based ligand and its oxidized derivatives. Inorg Chem 51:12720-8

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