Structural requirements for oxidation of low-density lipoprotein by thiols.

Oxidation of low-density lipoprotein (LDL) by macrophages, endothelial cells and smooth muscle cells, may be mediated by production of free thiols in the presence of transition metals. We examined the structural requirements, within a series of cysteinyl derivatives, for oxidation of thiols and of LDL in Hams F10 medium. The primary mechanism by which such thiols mediate oxidation of LDL is largely independent of superoxide production, but strongly correlated with the susceptibility of each thiol to iron-catalysed auto-oxidation. These effects are compared and contrasted with thiol-dependent oxidation of LDL by stimulated human monocytes and macrophages.