Lipid-Oxidative Enzymes and Fenton-Like Reactions Are Synergistic in Promoting Membrane Lipid Peroxidation.

Lipid peroxidation (LPO) of cellular membranes is a near-universal indicator of aging and disease, yet the mechanistic link between the LPO and disease remains elusive. In this study, we demonstrate that efficient LPO in model membranes is accomplished through synergy between selective enzymatic oxidation by lipoxygenase (LOX) and nonspecific oxidation by reactive oxygen species (ROS). Through fluorescence-based oxidation kinetic measurements, we show that soluble ROS alone fails to induce significant oxidation under physiologically relevant conditions. However, enzymatic oxidation enhances the ROS-driven LPO by altering membrane permeability. Strikingly, this process drives the macroscopic clustering of the membrane-bound protein KRAS on giant unilamellar vesicles (GUVs), revealing potential functional consequences. If this mechanism extends to living cells, it could reshape our understanding of oxidative stress in disease. Our findings represent an essential step toward advancing an integrated understanding of oxidative membrane biology, encompassing both enzymatic oxidation and oxidation by ROS.