Design and fabrication of recombinant reflectin-based multilayer reflectors: bio-design engineering and photoisomerism induced wavelength modulation.

The remarkable camouflage capabilities of cephalopods have inspired many to develop dynamic optical materials which exploit certain design principles and/or material properties from cephalopod dermal cells. Here, the angle-dependent optical properties of various single-layer reflectin thin-films on Si wafers are characterized within the UV-Vis-NIR regions. Following this, initial efforts to design, fabricate, and optically characterize a bio-inspired reflectin-based multilayer reflector is described, which was found to conserve the optical properties of single layer films but exhibit reduced angle-dependent visible reflectivity. Finally, we report the integration of phytochrome visible light-induced isomerism into reflectin-based films, which was found to subtly modulate reflectin thin-film reflectivity.

Rewiring the "Push-Pull" Catalytic Machinery of a Heme Enzyme Using an Expanded Genetic Code.

Nature employs a limited number of genetically encoded axial ligands to control diverse heme enzyme activities. Deciphering the functional significance of these ligands requires a quantitative understanding of how their electron-donating capabilities modulate the structures and reactivities of the iconic ferryl intermediates compounds I and II. However, probing these relationships experimentally has proven to be challenging as ligand substitutions accessible via conventional mutagenesis do not allow fine tuning of electron donation and typically abolish catalytic function. Here, we exploit engineered translation components to replace the histidine ligand of cytochrome c peroxidase (CcP) by a less electron-donating N δ-methyl histidine (Me-His) with little effect on the enzyme structure. The rate of formation (k 1) and the reactivity (k 2) of compound I are unaffected by ligand substitution. In contrast, proton-coupled electron transfer to compound II (k 3) is 10-fold slower in CcP Me-His, providing a direct link between electron donation and compound II reactivity, which can be explained by weaker electron donation from the Me-His ligand ("the push") affording an electron-deficient ferryl oxygen with reduced proton affinity ("the pull"). The deleterious effects of the Me-His ligand can be fully compensated by introducing a W51F mutation designed to increase "the pull" by removing a hydrogen bond to the ferryl oxygen. Analogous substitutions in ascorbate peroxidase lead to similar activity trends to those observed in CcP, suggesting that a common mechanistic strategy is employed by enzymes using distinct electron transfer pathways. Our study highlights how noncanonical active site substitutions can be used to directly probe and deconstruct highly evolved bioinorganic mechanisms.

Synthetic biology for fibres, adhesives and active camouflage materials in protection and aerospace.

Synthetic biology has huge potential to produce the next generation of advanced materials by accessing previously unreachable (bio)chemical space. In this prospective review, we take a snapshot of current activity in this rapidly developing area, focussing on prominent examples for high-performance applications such as those required for protective materials and the aerospace sector. The continued growth of this emerging field will be facilitated by the convergence of expertise from a range of diverse disciplines, including molecular biology, polymer chemistry, materials science and process engineering. This review highlights the most significant recent advances and address the cross-disciplinary challenges currently being faced.