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Nanoscale ; 11(12): 5412-5421, 2019 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-30855041


To take peptide materials from predominantly structural to functional assemblies, variations in cofactor binding sites must be engineered and controlled. Here, we have employed the peptide sequence c16-AHX3K3-CO2H where X3 represents the aliphatic structural component of the peptide design that dictates ß-sheet formation and upon self-assembly yields a change in the overall microenvironment surrounding the Zn protoporphyrin IX ((PPIX)Zn) binding site. All peptides studied yield ß-sheet rich nanofibers highlighting the materials' resiliency to amino acid substitution. We highlight that the (PPIX)Zn binding constants correlate strongly with amino acid side chain volume, where X = L or I yields the lowest dissociation constant values (KD). The resulting microenvironment highlights the materials' ability to control interchromophore electronic interactions such that slip-stacked cofacial arrangements are observed via exciton splitting in UV/visible and circular dichroism spectroscopy. Steady state and time-resolved photoluminescence suggests that greater interchromophore packing yields larger excimer populations and corresponding longer excimer association lifetimes (τA) which directly translates to shorter exciton diffusion lengths. In comparison to synthetic porphyrin molecular assemblies, this work demonstrates the ability to employ the peptide assembly to modulate the degree of cofactor arrangement, extent of excimer formation, and the exciton hopping rates all while in a platform amenable for producing polymer-like materials.

Nanofibras/química , Peptídeos/química , Protoporfirinas/química , Sítios de Ligação , Dicroísmo Circular , Microscopia Eletrônica de Transmissão , Ligação Proteica , Conformação Proteica em Folha beta , Espectrofotometria
Org Biomol Chem ; 15(32): 6725-6730, 2017 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-28782067


Nature guides the flow of electrons in biological systems with the assistance of multi-heme proteins called cytochromes. In an effort to understand natures approach to developing electronic systems, three peptides that are compositionally identical but sequentially distinct have been designed to study the impact of morphology and hydrophobicity on heme coordination and function.

Citocromos/síntese química , Elétrons , Heme/química , Sítios de Ligação , Citocromos/química , Interações Hidrofóbicas e Hidrofílicas , Substâncias Macromoleculares/síntese química , Substâncias Macromoleculares/química