Lipid peroxidation causes an increase of lipid order and a decrease of 5'-nucleotidase activity in the liver plasma...

Area of Science:

• Biochemistry
• Cell Biology
• Membrane Biophysics

Background:

• 5'-nucleotidase is an ectoenzyme crucial for cellular signaling and nucleotide metabolism.
• Membrane microviscosity, a measure of lipid bilayer fluidity, influences protein function and membrane dynamics.
• Oxidative stress can alter membrane structure and enzyme activity.

Purpose of the Study:

• To investigate the impact of peroxidation on 5'-nucleotidase activity.
• To examine the effect of peroxidation on liver plasma membrane microviscosity.
• To determine the relationship between altered membrane microviscosity and 5'-nucleotidase activity.

Main Methods:

• Liver plasma membranes from Wistar rats were subjected to peroxidation using hydrogen peroxide (H2O2) and ferrous sulfate (FeSO4) or t-butylhydroperoxide.
• Membrane microviscosity was assessed using fluorescent lipid probes (DPH, PA-DPH) and a thiol reagent (1-PM).
• 5'-nucleotidase activity was measured following peroxidation treatments.

Main Results:

• Peroxidation significantly increased membrane microviscosity, indicated by elevated transition temperatures of fluorescent probes.
• The activity of 5'-nucleotidase was decreased following peroxidation.
• A correlation was observed between increased membrane microviscosity and reduced 5'-nucleotidase activity.

Conclusions:

• Peroxidation induces changes in liver plasma membrane structure, leading to increased microviscosity.
• The observed decrease in 5'-nucleotidase activity is likely regulated by the increased membrane microviscosity.
• These findings highlight the role of membrane biophysical properties in modulating enzyme function under oxidative stress.