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A decrease of lipid fluidity of the porcine intestinal brush-border membranes by treatment with malondialdehyde
T Ohyashiki1, N Sakata, K Matsui
1Department of Biochemistry, School of Pharmacy, Hokuriku University, Ishikawa.
Abstract:
The effect of treatment of the porcine intestinal brush-border membranes with malondialdehyde (MDA) on their lipid fluidity was examined using a fluorescence probe, 1,6-diphenyl-1,3,5-hexatriene (DPH). When the membranes were treated with MDA, the fluorescence anisotropy of DPH-labeled membranes increased and the amount of DPH molecules incorporated into the membranes decreased from 3.25 to 2.23 nmol/mg protein. In addition, the response of the fluorescence anisotropy of DPH-labeled membranes to benzyl alcohol, a well-known fluidizer, was markedly suppressed by treatment of the membranes with MDA. These results suggest that treatment of the membranes with MDA causes a decrease of the membrane lipid fluidity. This interpretation was further supported by the increase observed in the fluorescence anisotropy of DPH-labeled liposomes prepared from the extracted lipids of MDA-treated membranes. The results of SDS-polyacrylamide gel electrophoresis suggested that the formation of high-molecular-weight aggregates of the membrane proteins is not involved in the increase of the fluorescence anisotropy of DPH-labeled membranes by treatment with MDA. On the basis of these results, changes in the physical properties of the intestinal brush-border membranes by treatment with MDA are discussed.
Insights
Malondialdehyde (MDA) treatment decreases intestinal brush-border membrane fluidity by altering lipid packing. This impacts membrane physical properties, as evidenced by fluorescence probe studies.
Area of Science:
- Biochemistry
- Membrane Biology
- Physiology
Background:
- Porcine intestinal brush-border membranes are crucial for nutrient absorption.
- Lipid fluidity is a key determinant of membrane function.
- Malondialdehyde (MDA) is an indicator of lipid peroxidation and can alter membrane properties.
Purpose of the Study:
- To investigate the effect of malondialdehyde (MDA) on the lipid fluidity of porcine intestinal brush-border membranes.
- To elucidate the biophysical changes induced by MDA in membrane structure.
Main Methods:
- Utilized 1,6-diphenyl-1,3,5-hexatriene (DPH) as a fluorescence probe to measure membrane anisotropy.
- Assessed the impact of benzyl alcohol, a known fluidizer, on DPH-labeled membranes.
- Prepared liposomes from extracted lipids of MDA-treated membranes for further analysis.
- Employed SDS-polyacrylamide gel electrophoresis to examine membrane protein aggregation.
Main Results:
- MDA treatment increased DPH fluorescence anisotropy, indicating reduced lipid fluidity.
- The incorporation of DPH into membranes decreased following MDA treatment.
- The fluidizing effect of benzyl alcohol on membranes was suppressed by MDA.
- Liposomes from MDA-treated membranes showed increased DPH fluorescence anisotropy.
- SDS-PAGE indicated that protein aggregation was not responsible for the observed changes.
Conclusions:
- Malondialdehyde (MDA) treatment significantly decreases the lipid fluidity of porcine intestinal brush-border membranes.
- MDA alters the physical properties of the membrane, likely through direct interaction with lipids.
- These findings contribute to understanding the detrimental effects of oxidative stress on intestinal membrane integrity and function.