Apolipoprotein B inhibits the hemolytic activity of asp-hemolysin from Aspergillus fumigatus
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Abstract:
We investigated the effect of human blood plasma lipoproteins on the hemolytic activity of Asp-hemolysin. Apolipoprotein B (apoB)-containing lipoproteins, such as low density lipoprotein (LDL) and very low density lipoprotein (VLDL), inhibit the activity of this hemolytic toxin. When Asp-hemolysin (15 mu g) was incubated with 100 mu g LDL (as protein), the hemolytic activity was inhibited by 90%. When 20 mu g apoB was added, the hemolytic activity was almost completely inhibited. Furthermore, similar inhibition was obtained in the filtrates which were separated from the incubation mixture of Asp-hemolysin with LDL or apoB following ultrafiltration through a membrane with a molecular cutoff = 100000. The current findings suggest that the inhibition by LDL is due to apoB binding to Asp-hemolysin.
Insights
Human plasma lipoproteins, specifically apolipoprotein B (apoB)-containing ones like LDL, significantly inhibit Asp-hemolysin
Area of Science:
- Biochemistry
- Toxicology
- Lipid Metabolism
Background:
- Asp-hemolysin is a toxin known for its hemolytic activity.
- Human blood plasma contains various lipoproteins, including those with apolipoprotein B (apoB).
Purpose of the Study:
- To investigate the impact of human plasma lipoproteins on Asp-hemolysin's hemolytic activity.
- To determine the role of apolipoprotein B in this interaction.
Main Methods:
- Incubation of Asp-hemolysin with low-density lipoprotein (LDL) and apolipoprotein B (apoB).
- Quantification of hemolytic activity after incubation.
- Ultrafiltration to separate components based on molecular weight.
Main Results:
- Apolipoprotein B (apoB)-containing lipoproteins, such as LDL and very low-density lipoprotein (VLDL), inhibit Asp-hemolysin's hemolytic activity.
- Incubation with LDL (100 μg protein) reduced hemolytic activity by 90%.
- Addition of apoB (20 μg) almost completely inhibited hemolytic activity, suggesting apoB is the inhibitory component.
Conclusions:
- Apolipoprotein B (apoB) in lipoproteins like LDL plays a key role in inhibiting Asp-hemolysin's hemolytic activity.
- The inhibitory effect is attributed to the binding of apoB to Asp-hemolysin.