The interaction of amino‐deuteromethylated melittin with phospholipid membranes studied by deuterium NMR

Abstract

Melittin, deuteromethylated on each of the four amino groups (Gly-1 Not and Lys-7, 21, and 23 Are), was prepared by reductive methylation using deuteroformaldehyde and NaBD3CN. Deuterium NMR spectra were obtained for the modified peptide (D-melittin) bound to phospholipid bilayers and erythrocyte ghosts. D-Melittin at 4 mol% (peptide:lipid) induced reversible transitions between extended bilayers and micelles at the phase-transition temperature in dimyristoylphosphatidylcholine (DMPC) bilayers. These changes in lipid morphology did not occur at 1 mol% D-melittin: DMPC and the peptide was highly motionally restricted in gel-phase lipid.

A deuterium and phosphorus-31 nuclear magnetic resonance study of the interaction of melittin with dimyristoylphosphatidylcholine bilayers and the effects of contaminating phospholipase A2

“…Preparation of melittin-DMPC complexes by suspending the lipid in melittin-containing buffer above the lipid phase transition temperature resulted in rapid attainment of equilibrium so that reproducible temperature runs could be obtained within 30 min of sample preparation. Similarly, all of the melittin was associated with the lipid at concentrations up to at least 4 mol % as determined by deuterium NMR experiments using selectively deuteriated melittin (Dempsey et al, 1987). Each of these findings is in contrast to previous reports either that equilibrium is attained only under specific conditions or after long incubation periods (Prendergast et al, 1982) or that DMPC is able to support only up to 2 mol % of melittin (Vogel, 1981).…”

NMR methods for studying membrane‐active antimicrobial peptides

“…Either the label is introduced during synthesis or by chemical modification at a covalent position, or some hydrogen-bonded protons are exchanged in 2 H 2 O. In an early 2 H NMR study, melittin was amino-deuteromethylated by attaching CD 3 groups to the lysine side chains and the N-terminal amino group (101). Several splittings were observed and found to change depending on the lipid charge and temperature, but the splittings were not assigned.…”