Tunable Energy Transfer Rates via Control of Primary, Secondary, and Tertiary Structure of a Coiled Coil Peptide Scaffold

Abstract

Herein we report energy transfer studies in a series of Ru(II) and Os(II) linked coiled-coil peptides in which the supramolecular scaffold controls the functional properties of the assembly. A general and convergent method for the site-specific incorporation of bipyridyl Ru(II) and Os(II) complexes using solid-phase peptide synthesis and the copper-catalyzed azide-alkyne cycloaddition is reported. Supramolecular assembly positions the chromophores for energy transfer. Using time-resolved emission spectroscopy we measured position-dependent energy transfer that can be varied through changes in the sequence of the peptide scaffold. High level molecular dynamics simulations were used in conjunction with the spectroscopic techniques to gain molecular-level insight into the observed trends in energy transfer. The most efficient pair of Ru(II) and Os(II) linked peptides as predicted by molecular modeling also exhibited the fastest rate of energy transfer (with k(EnT) = 2.3 × 10(7) s(-1) (42 ns)). Additionally, the emission quenching for the Ru(II) and Os(II) peptides can be fit to binding models that agree with the dissociation constants determined for the peptides via chemical denaturation.

Artificial photosynthesis: Where are we now? Where can we go?

“…As shown in Figure 7, they include surface assembled structures including a molecular overlayer (Figure 7A), 76 co-loaded (Figure 7E), 77 layer-by-layer (Figure 7C), [78][79][80] and electro-assembly structures (Figure 7B) 81,82 . They also include pre-formed assemblies based on peptide scaffolds (Figure 7D), 85,86 and polymer scaffolds (Figure 7F), 83,84 and covalently linked molecular assemblies (Figure 6 A&B). 75,[87][88][89][90][91][92] .…”

Synthesis and Self-Assembly of Bundle-Forming α-Helical Peptide–Dendron Hybrids

“…20 Residues on the exterior of the bundle minimally contribute to the folding and assembly of helix bundle-forming peptides, which makes these residues convenient sites to which prosthetic groups can be conjugated. Indeed, polymers, 21 catalysts, 22 and other groups 23 have been appended to exterior positions of helical bundles.…”

De Novo Design of Xeno‐Metallo Coiled Coils

“…[31] The shape and rigidity of the CC scaffold allowed them to controlt he spatial alignment between the two centers, positioning the chromophores for efficient energy transfer,at hemew hich has previously been explored in this focus review. [31]…”

“…Not surprisingly, non‐proteinogenic amino acids with side chains which feature either the alkyne or azide have been developed for use in SPPS. For example, Waters and co‐workers introduced Ru II and Os II complexes, covalently linked to the CC via azide–alkyne ‘click’ chemistry, at well‐defined distances from one another . The shape and rigidity of the CC scaffold allowed them to control the spatial alignment between the two centers, positioning the chromophores for efficient energy transfer, a theme which has previously been explored in this focus review …”