Solar energy conversion of water into the environmentally clean fuel hydrogen offers one best long-term solutions for meeting future demands. Nature provides highly evolved, finely tuned molecular machinery solar that exquisitely manages photon capture and processes to drive oxygenic water-splitting carbon fixation. Herein, we use Nature's specialized energy-converters, Photosystem I (PSI) protein, production from a synthetic catalyst comprised inexpensive, earth-abundant materials. PSI...

Structural insights have been provided by mercury-199 nuclear magnetic resonance (NMR) into the metal receptor site of MerR metalloregulatory protein alone and in a complex with regulatory target, DNA. The one- two-dimensional NMR data are consistent trigonal planar Hg-thiolate coordination environment consisting only Cys side chains resolve structural aspects both ion recognition allosteric mechanism. These studies establish 199 Hg techniques as useful probes proteins, copper enzymes, zinc...

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTDe Novo Design of Mercury-Binding Two- and Three-Helical BundlesGregg R. Dieckmann, Donald K. McRorie, David L. Tierney, Lisa M. Utschig, Christopher P. Singer, Thomas V. O'Halloran, James E. Penner-Hahn, William F. DeGrado, Vincent PecoraroView Author Information Department Chemistry, University Michigan Ann Arbor, 48109-1055 Research Applications Beckman Instruments, Inc. 1050 Page Mill Road, Palo Alto, California 94304 Northwestern...

A photocatalytic hydrogen-evolving system based on intermolecular electron transfer between native Photosystem I (PSI) and electrostatically associated Pt nanoparticles is reported. Using cytochrome c6 as the soluble mediator ascorbate sacrificial donor, visible-light-induced H2 production occurs for PSI/Pt nanoparticle biohybrids at a rate of 244 μmol (mg chlorophyll)−1 h−1 or 21 034 mol (mole PSI)−1 h−1. These results demonstrate that highly efficient photocatalysis can be obtained...

The direct conversion of sunlight into fuel is a promising means for the production storable renewable energy. Herein, we use Nature's specialized photosynthetic machinery found in Photosystem I (PSI) protein to drive solar from nickel diphosphine molecular catalyst. Upon exposure visible light, self-assembled PSI-[Ni(P2(Ph)N2(Ph))2](BF4)2 hybrid generates H2 at rate 2 orders magnitude greater than rates reported photosensitizer/[Ni(P2(Ph)N2(Ph))2](BF4)2 systems. environment enables...

Non-noble-metal, thin-film oxides are widely investigated as promising catalysts for oxygen evolution reactions (OER). Amorphous cobalt oxide films electrochemically formed in the presence of borate (CoBi) and phosphate (CoPi) share a common cobaltate domain building block, but differ significantly OER performance that derives from different electron–proton charge transport properties. Here, we use combination L edge synchrotron X-ray absorption (XAS), resonant emission (RXES), inelastic...

Silver metal nanoparticle (NP) enhanced fluorescence is investigated in thin films of cyanobacterial Photosystem I trimer complexes (PSI) by correlating confocal laser scanning microscopy, dark-field imaging, and lifetime measurements. PSI represents an interesting light-harvesting complex with a 20 nm diameter that not uniformly contained within the surface-localized plasmon field NPs. With weak far-field illumination, 5- to 20-fold enhancement observed for adjacent NPs, arising from...

ConspectusPhotosynthetic reaction center (RC) proteins convert incident solar energy to chemical through a network of molecular cofactors which have been evolutionarily tuned couple efficient light-harvesting, directional electron transfer, and long-lived charge separation with secondary sequences. These are embedded within complex protein environment precisely positions each cofactor in optimal geometries along transfer pathways localized environments facilitating sequential accumulative...

Bacterial microcompartments (BMCs) are self-assembling, selectively permeable protein shells that encapsulate enzymes to enhance catalytic efficiency of segments metabolic pathways through means confinement. The modular nature BMC shells' structure and assembly enables programming shell permeability underscores their promise in biotechnology engineering efforts for applications industry, medicine, clean energy. Realizing this potential requires methods encapsulation abiotic molecules, which...

Microsecond coherence times are predicted in spin dynamics calculations of a donor–acceptor electron pair P+A1A− created upon light excitation photosystem I (PSI). The effects nuclear diffusion (NSD) due to the anisotropic protein environment on TM studied. Closely positioned pairs and triples protons located 5–8 Å from shown largely control TM. Knowledge crystal structure PSI allows for where specific cofactors amino acid residues removed or replaced identification environmental features...

Photosynthetic reaction center proteins (RCs) provide ideal model systems for studying quantum entanglement between multiple spins, a mechanical phenomenon wherein the properties of entangled particles become inherently correlated. Following light-generated sequential electron transfer, RCs generate spin-correlated radical pairs (SCRPs), also referred to as spin qubit (radical) (SQPs). Understanding and controlling coherence mechanisms in SCRP/SQPs is important realizing practical uses...

Directed assembly of abiotic catalysts onto biological redox protein frameworks is interest as an approach for the synthesis biohybrid that combine features both synthetic and materials. In this report, we provide a multiscale characterization platinum nanoparticle (NP) hydrogen-evolving are assembled by light-driven reductive precipitation from aqueous salt solution photosystem I (PSI), isolated cyanobacteria trimeric PSI. The resulting PSI-NP assemblies were analyzed using combination...

Bacterial microcompartments (BMCs) are proteinaceous organelles that self-assemble into selectively permeable shells encapsulate enzymatic cargo. BMCs enhance catalytic pathways by reducing crosstalk among metabolites, preventing harmful intermediates from leaking the cytosol and increasing reaction efficiency via enzyme colocalization. The intrinsic properties of make them attractive for biotechnological engineering. However, in vivo expression methods shell synthesis have significant...

Efficient charge separation occurring within membrane-bound reaction center proteins is the most important step of photosynthetic solar energy conversion. All centers are classified into two types, I and II. X-ray crystal structures reveal that both types bind symmetric membrane-spanning branches potential electron-transfer cofactors. Determination functional roles these pairs fundamental importance. While it established in type II only one branch functions electron transfer, we present...

Long-lived charge separation facilitates photocatalytic H₂ production in a mini reaction center/catalyst complex.

Electron spin polarized electron paramagentic resonance (ESP EPR) spectra were obtained with deuterated iron-removed photosynthetic bacterial reaction centers (RCs) to specifically investigate the effect of rate primary charge separation, metal-site occupancy, and H-subunit content on observed P865+QA- charge-separated state. Fe-removed Zn-substituted RCs from Rb. sphaeroides R-26 prepared by refined procedures, specific transfer rates (kQ) intermediate acceptor H- QA (200 ps)-1 vs (3−6...

Two ruthenium-protein-cobaloxime biohybrids produce photocatalytic hydrogen through different catalytic pathways characterized by EPR and transient optical spectroscopies.

Isolated reaction centers (RCs) from Rhodobacter sphaeroides were found to bind Zn(II) stoichiometrically and reversibly in addition the 1 equiv of non-heme Fe(II). Metal EPR analyses confirm that is ligated a binding site distinct Fe site. When bound this site, electron transfer between quinones QA QB (QA-QB → QAQB-) slowed room-temperature kinetics become distributed across microsecond millisecond time domain. This effect metal on similar more global cooling RCs 2 °C absence Zn(II)....

A new photocatalytic system composed of abiotic catalyst and native photosynthetic membranes produces hydrogen oxygen directly from water using sunlight.

Enhanced spectral resolution of high-frequency electron paramagnetic resonance (EPR) spectroscopy allows for detailed g-tensor analysis the active pigments in photosynthetic reactio...

The direct creation of a fuel from sunlight and water via photochemical energy conversion provides sustainable method for producing clean source energy. Here we report the preparation solar biohybrid that embeds nickel diphosphine hydrogen evolution catalyst into cofactor binding pocket electron shuttle protein, flavodoxin (Fld). system is made photocatalytic by linking cysteine residue in Fld to ruthenium photosensitizer. Importantly, protein environment enables otherwise insoluble Ni...

The cobalt–phosphate amorphous oxyhydroxide water-splitting catalyst, CoPi, is widely investigated because of its reactivity and self-repair analogous to the oxygen-evolving catalyst in Photosystem II. CoPi films show optical absorption features those seen more generally transition metal oxides catalysts. Possible photocatalytic properties have, up until now, not been considered. Herein, we report on finding wavelength-dependent photo-electrochemical responses CoPi. Red light excitation (623...