CD and 31P NMR studies of tachykinin and MSH neuropeptides in SDS and DPC micelles

• CD spectral properties of SP, NKA, NKB, α-MSH, γ1-MSH, γ2-MSH, and melittin were evaluated in phosphite buffer, DPC, and SDS.
• 31P NMR results of DPC micelles with these peptides are reported.
• CD spectral shapes are in SDS are correlated with a peptide's cationic character.

Secondary structural characteristics of substance P (SP), neurokinin A (NKA), neurokinin B (NKB), α-melanocyte stimulating hormone peptide (α-MSH), γ1-MSH, γ2-MSH, and melittin were evaluated with circular dichroism in phosphite buffer, DPC micelles, and SDS micelles. CD spectral properties of γ1-MSH and γ2-MSH as well as 31P NMR of DPC micelles with all the peptides are reported for the first time. Although, a trend in the neuropeptide/micelle CD data appears to show increased α-helix content for the tachykinin peptides (SP, NKA, NKB) and increased β-sheet content for the MSH peptides (α-MSH, γ1-MSH, γ2-MSH) with increasing peptide charge, the lack of perturbed 31P NMR signals for all neuropeptides could suggest that the reported antimicrobial activity of SP and α-MSH might not be related to a membrane disruption mode of action.

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