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Spermine accelerates iron-induced lipid peroxidation in mitochondria by modification of membrane surface charge
K Kogure1, K Fukuzawa, H Kawano
1Faculty of Pharmaceutical Sciences, University of Tokushima, Japan.
Abstract:
The polyamine spermine was found to make the mitochondrial membrane more susceptible to lipid peroxidation induced by adenosine 5'-diphosphate (ADP)/Fe2+. It shortened the lag time before induction of peroxidation, but did not affect the rate of lipid peroxidation. It had no effect on lipid peroxidation of electrically neutral egg yolk phosphatidylcholine liposomes, but had an effect on lipid peroxidation of negatively charged liposomes consisting of egg yolk phosphatidylcholine and bovine heart cardiolipin similar to that on peroxidation in mitochondria. Spermine decreased the negative zeta-potential of these negatively charged liposomes consisting of phosphatidylcholine and cardiolipin. These results suggest that the hydrophilic polycation spermine reduces the negative charge on the surface of mitochondrial membrane, possibly by its interaction with negatively charged polar heads of phospholipids, and that this neutralization of the surface charge renders the mitochondrial membrane more susceptible to induction of lipid peroxidation induced by ADP/Fe2+.
Insights
The polyamine spermine increases mitochondrial membrane susceptibility to lipid peroxidation by reducing surface charge. This finding is crucial for understanding oxidative stress in mitochondria.
Area of Science:
- Biochemistry
- Mitochondrial Biology
- Oxidative Stress
Background:
- Mitochondrial membranes are susceptible to lipid peroxidation, a process implicated in cellular damage.
- Polyamines, like spermine, are involved in various cellular functions, but their role in mitochondrial lipid peroxidation is not fully understood.
Purpose of the Study:
- To investigate the effect of spermine on mitochondrial membrane susceptibility to lipid peroxidation.
- To elucidate the mechanism by which spermine influences lipid peroxidation in mitochondria.
Main Methods:
- Lipid peroxidation assays were performed on isolated mitochondria and liposomes (neutral and negatively charged).
- Zeta-potential measurements were used to assess surface charge modifications.
- Lipid peroxidation was induced using adenosine 5'-diphosphate (ADP)/Fe2+.
Main Results:
- Spermine shortened the lag time for lipid peroxidation induction in mitochondria but did not alter the rate.
- Spermine affected lipid peroxidation in negatively charged liposomes similarly to mitochondria, but not in neutral liposomes.
- Spermine decreased the negative zeta-potential of negatively charged liposomes.
Conclusions:
- Spermine enhances mitochondrial membrane susceptibility to ADP/Fe2+-induced lipid peroxidation.
- This effect is likely due to spermine neutralizing the negative surface charge of the mitochondrial membrane.
- The interaction of spermine with negatively charged phospholipids on the membrane surface plays a key role.