Functional characterization of a melittin analog containing a non‐natural tryptophan analog

• DOI: 10.1002/bip.22624
• Publication Date: 2015-02-09T09:15:43Z
• Authors: Zachary Ridgway; Angela L. Picciano; Pallavi M. Gosavi; Yurii S. Moroz; Christopher E. An...; Amy E. Chavis; Joseph E. Reiner; Ivan V. Korendovych; Gregory A. Caputo
• Keywords: Melittin; Alanine

ABSTRACT Tryptophan (Trp) is a naturally occurring amino acid, which exhibits fluorescence emission properties that are dependent on the polarity of local environment around Trp side chain. However, this sensitivity also complicates interpretation data. A non‐natural analogue tryptophan, β‐(1‐azulenyl)‐L‐alanine, insensitive to solvent and does not impact structure or characteristics several peptides examined. In study, we investigated effect replacing with β‐(1‐azulenyl)‐L‐alanine in well‐known bee‐venom peptide melittin. This provides model framework for investigating functional system undergoes significant shifts upon binding lipid bilayers. Microbiological methods including assessment antimicrobial activity by minimal inhibitory concentration (MIC) assays bacterial membrane permeability indicated little difference between β‐(1‐azulenyl)‐L‐alanine‐substituted versions Circular dichroism spectroscopy showed both adopted expected α‐helical structures when bound phospholipid bilayers electrophysiological analysis created disruptions leading conductance increases across membranes. Both exhibited marked protection respective fluorophores indicating similar membrane‐bound topology. As expected, while quenching CD indicate stably vesicles, containing no shift natural >10 nm spectrum barycenter. Taken together, can serve as alternative have impacts function interacting peptides. © 2015 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 104: 384–394, 2015.