Contribution of proline-14 to the structure and actions of melittin |
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Authors: | C E Dempsey R Bazzo T S Harvey I Syperek G Boheim I D Campbell |
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Institution: | Biochemistry Department, Oxford University, UK. |
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Abstract: | The structure and dynamic properties of bee venom melittin and a synthetic analogue, Ala14]-melittin (melittin P14A), are compared, using high resolution 1H nuclear magnetic resonance (NMR) spectroscopy and amide exchange measurements in methanol. P14A is shown to adopt a regular, stable alpha-helical conformation in solution without the flexibility around the Pro-14 residue found in melittin. P14A has twice the hemolytic activity of melittin but is less able to induce voltage-dependent ion conductance in planar bilayers. The results indicate that helix flexibility afforded by the Pro-14 residue promotes the ability of melittin to adopt the transbilayer associates thought to underlie ion translocation. |
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