Binding of annexin V to membrane products of lipid peroxidation

There is increasing evidence that endogenously generated aldehydes formed a s a result of lipid peroxidation are involved in the pathophysiological eff ects associated with oxidative stress in cells and tissues. Malondialdehyde (MDA), a major product of lipid peroxidation, can modify amines present on the cell surface and thereby introduce negative charges that can affect th e interfacial ionic layer. We show that lipid peroxidation of RBC generates MDA adducts that, similar to phosphatidylserine (PS), bind annexin V in a Ca2+-dependent manner. Like PS, these adducts also promote the "PS-dependen t" prothrombinase assays, albeit to lower levels, These results indicate th at annexin V binding cannot be used as an exclusive indicator of cell surfa ce PS and raise the possibility that some phenomenon attributed to PS may, in fact, also involve aldehyde-lipid adducts.