Abstract
Several amphipathic and cationic substances are known to bind lipid A, the toxic component of bacterial lipopolysaccharides. In this report, we have characterized, by fluorescence methods, the interaction of melittin, an amphipathic and basic 26-residue polypeptide isolated from bee venom, with lipid A. The stoichiometry of the complex appears to be two molecules of melittin to one of lipid A with a dissociation constant of 2.5 × 10 -6 M. The binding of melittin not only modifies the endotoxic properties of lipid A in a number of biological assays, but also results in abrogation of the hemolytic activity of melittin. A model of the complex is proposed based on the known structures of lipid A and melittin, and the observed stoichiometry of binding.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 269-274 |
| Number of pages | 6 |
| Journal | Biochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism |
| Volume | 1123 |
| Issue number | 3 |
| DOIs | |
| State | Published - Feb 12 1992 |
Bibliographical note
Funding Information:work was supporteda lso by funds from The Wellcome Trust, London and The Rockefeller Foundation, New York. S.D. is a recipient of a Senior ResearchF ellow-ship from The Council for Scientific and Industrial Research, Government of India. The authors are gratefult o Dr. A. Cariappaf or help with the mitogenic assaysa nd to Dr. Vinod Mishra for assistancew ith fluorescencee xperiments.
Keywords
- Fluorescence
- Lipid A
- Lipopolysaccharide
- Melittin