Structural features and conformational equilibria of 3₁₀‐helical peptides in solution by spectroscopic and molecular mechanics studies

Abstract

The structural features and conformational equilibria of a series of short, linear Calpha-methylvaline [(alphaMe)Val]-based peptides in methanol were investigated by combining fluorescence resonance energy transfer measurements and molecular mechanics data. IR spectra were employed to determine their secondary structure, which exhibits an intramolecularly H-bonded, 3(10)-helix conformation that is affected by backbone distortions that are enhanced by the shortness of the main chain.

Mechanism of Membrane Activity of the Antibiotic Trichogin GA IV: A Two-State Transition Controlled by Peptide Concentration

“…The RET phenomenon has an inverse sixth power dependence on distance, with a 50% quenching efficiency at an interprobe distance called the Förster radius (Pispisa et al, 2002b(Pispisa et al, , 2003. In the case of the fluorene-NBD pair this distance is 24 Å , whereas the thickness of the bilayer is 42 Å (Lis et al, 1982).…”

Structural properties and photophysical behavior of conformationally constrained hexapeptides functionalized with a new fluorescent analog of tryptophan and a nitroxide radical quencher

“…A successful strategy to design peptide sequences exhibiting controlled secondary structures is that of using C α,α ‐dialkylated glycyl residues as building blocks 4, 5. This synthetic approach opened the route to a variety of applications, spanning from the design of new peptidomimetic drugs (hormones, neurotransmitters, enzymes)6, 7 to the endowment of the peptide template with interesting chemical functionalities (energy/electron donor–acceptor pair, catalytic sites) 8–10. In intramolecular electron‐transfer processes, a rigid peptide framework may not simply act as a spacer between the donor and acceptor groups, but also promote the electronic coupling between the redox pair 11–14.…”

Conformational Behavior and Magnetic Properties of a Nitroxide Amino Acid Derivative in Vacuo and in Aqueous Solution

“…2 A favorable property of TOAC over other spinlabeled amino acids is that rotation about side-chain bonds is hampered by the incorporation of the nitroxide nitrogen, C R , C β , and C γ atoms into a cyclic moiety. [3][4][5] TOAC is able to induce a dramatic quenching of suitably designed, fluorescence-labeled peptides 6,7 and is characterized by a weak ( ) 5-20) adsorption band in the visible spectral region (λ ) 420-450 nm), assigned to the n f π* transition of the nitroxide chromofore, which may become optically active in a chiral peptide and be detected by CD. 8 Furthermore, it is able to undergo a reversible, nitroxide-based redox process that can be monitored by cyclic voltammetry and gives derivatives and peptides of extremely high crystallinity, whose structures have been characterized by X-ray diffraction.…”