The carbon monoxide complex of [NiFe]hydrogenase from Desulfovibrio vulgaris Miyazaki F has been characterized by X-ray crystallography and absorption resonance Raman spectroscopy. Nine crystal structures the in CO-bound CO-liberated forms were determined at 1.2−1.4 Å resolution. exogenously added CO was assigned to be bound Ni atom Ni−Fe active site. not replaced with H2 dark 100 K, but liberated illumination a strong white light. Ni−C distances Ni−C−O angles about 1.77 160°, respectively,...

Cytochrome c (cyt ) is a stable protein that functions in monomeric state as an electron donor for cytochrome oxidase. It also released to the cytosol when permeabilization of mitochondrial outer membrane occurs at early stage apoptosis. For nearly half century, it has been known cyt forms polymers, but polymerization mechanism remains unknown. We found polymers by successive domain swapping, where C-terminal helix displaced from its original position monomer and Met-heme coordination...

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTCrystal Structure and Reversible O2-Binding of a Room Temperature Stable μ-η2:η2-Peroxodicopper(II) Complex Sterically Hindered Hexapyridine Dinucleating LigandMasahito Kodera, Kou Katayama, Yoshimitsu Tachi, Koji Kano, Shun Hirota, Shuhei Fujinami, Masatatu SuzukiView Author Information Department Molecular Science Technology Doshisha University, Kyotanabe, Kyoto 610-0321, Japan Chemistry, Graduate School Nagoya Chikusa-ku, 464-01, Kanazawa...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTime-resolved resonance Raman elucidation of the pathway for dioxygen reduction by cytochrome c oxidaseTakashi Ogura, Satoshi Takahashi, Shun Hirota, Kyoko Shinzawa-Itoh, Shinya Yoshikawa, Evan H. Appelman, and Teizo KitagawaCite this: J. Am. Chem. Soc. 1993, 115, 19, 8527–8536Publication Date (Print):September 1, 1993Publication History Published online1 May 2002Published inissue 1 September...

ConspectusHydrogenases are metalloenzymes that catalyze proton reduction and H2 oxidation with outstanding efficiency. They model systems for bioinorganic chemistry, including low-valent transition metals, hydride proton-coupled electron transfer. In this Account, we describe how photochemistry infrared difference spectroscopy can be used to identify the dynamic hydrogen-bonding changes facilitate transfer in [NiFe]- [FeFe]-hydrogenase.[NiFe]-hydrogenase binds a heterobimetallic nickel/iron...

The role of the active site Cu(2+) phenylethylamine oxidase from Arthrobacter globiformis (AGAO) has been studied by substitution with other divalent cations, where we were able to remove >99.5% site. enzymes reconstituted Co(2+) and Ni(2+) (Co- Ni-AGAO) exhibited 2.2 0.9% activities, respectively, original Cu(2+)-enzyme (Cu-AGAO), but their K(m) values for amine substrate dioxygen comparable. X-ray crystal structures Co- Ni-AGAO solved at 2.0-1.8 A resolution. These revealed changes in...

A clear understanding of the dynamic events amyloid β peptide (Aβ) 1−42, such as folding, self-assembly, and aggregation processes, would be great significance in Alzheimer's disease (AD) research. However, elucidation these Aβ1−42 is a difficult issue due to uncontrolled polymerization, which also poses significant obstacle for establishing an experimental system that clarifies pathological function Aβ1−42. On basis O-acyl isopeptide method, we herein developed novel photo-triggered "click...

Reversible binding of dioxygen occurs in aqueous solution to a myoglobin model composed porphinato iron(II) compound and per-O-methylated β-cyclodextrin dimer with pyridine linker (see picture). The affinity this system is 17.5±1.7 Torr the half-life O2 adduct 30.1 h phosphate buffer at pH 7 25 °C.

It has been experimentally shown that the folding of apoplastocyanin (apoPC) accompanies a very large enthalpic loss [N. Baden et al., J. Chem. Phys. 127, 175103 (2007)]. This implies an even larger entropic gain occurs in stabilizing folded structure to overcome loss. Here, we calculate water-entropy upon apoPC using angle-dependent integral equation theory combined with multipolar water model and recently developed morphometric approach. is demonstrated calculated value quantitatively good...

The 1:1 inclusion complex of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphinato iron(II) (FeIITPPS) and an O-methylated β-cyclodextrin dimer having a pyridine linker (1) binds dioxygen reversibly in aqueous solution. O2 adduct was very stable (t1/2 = 30.1 h) at pH 7.0 25 °C. ESI-MS NMR spectroscopic measurements molecular mechanics (MM) calculations indicated the sulfonatophenyl groups 5- 15-positions FeIIITPPS or FeIITPPS into two cyclodextrin moieties 1 to form supramolecular (hemoCD1 for...

An L-phenylalanyl chloromethylketone-based inhibitor equipped with a Hoveyda–Grubbs catalyst moiety was regioselectively incorporated into the cleft of α-chymotrypsin through intrinsic inhibition mechanism protein to construct an artificial organometallic protein.

The peroxidase activity of horse cytochrome c was enhanced by its dimerization, where Compound III (oxy-form) and I (oxoferryl porphyrin π-cation radical) species were detected in the reactions with hydrogen peroxide meta-chloroperbenzoic acid, respectively. These results show that oligomeric can contribute as a proapoptotic conformer increased activity.

The mechanism of the four-electron reduction dioxygen by a multicopper oxidase, CueO, was studied based on reactions single and double mutants with Cys500, type I copper ligand, noncoordinating Asp112 Glu506, which form hydrogen bonds trinuclear center directly indirectly via water molecule. reaction C500S containing vacant produced intermediate in an EPR-silent peroxide-bound form. formation from C500S/D112N restricted due to affinity for dioxygen. state realized be resting C500S/E506Q...

A new class of rhodamine luminophores, 3′,3″-bis(oxospiroisobenzofuran)-3,7-bis(dialkylamino)benzopyrano-xanthene derivatives (ABPX), have been successfully developed. The emission behavior ABPX series is directly opposite to the concentration quenching conventional dyes. exhibit aggregation-induced enhancement (AIEE).

The haemorrhage in the plaque (intraplaque haemorrhage) plays a critical role progression of atherosclerosis. purpose this study is to clarify whether aortic valve leaflet (intraleaflet accelerates stenosis (AS). We examined specimens leaflets obtained from 36 patients who had undergone replacement for degenerative AS and whom echocardiographic data were available just before operation at least 180 days last study. stenotic valves by immunohistochemistry detect intraleaflet with antibody...

Electrochemical response of photochromic tearylenes was surveyed by means cyclic voltammetry, DFT calculations, and spectroelectrochemistry. 4,5-Bis(2-phenyl-5-methylthiazolyl)-2-phenylthiazole found to show electrochemical oxidative ring-cycloreversion reaction. The net current efficiency the cycloreversion reaction under constant potential electrolysis as high 900%, which is ascribed an local-cell mechanism a chain mechanism. Electron transfer stopped-flow study using chemical oxidant...

NAD+ (oxidized form of NAD:nicotinamide adenine dinucleotide)-reducing soluble [NiFe]-hydrogenase (SH) is phylogenetically related to NADH (reduced NAD+):quinone oxidoreductase (complex I), but the geometrical arrangements subunits and Fe-S clusters are unclear. Here, we describe crystal structures SH in oxidized reduced states. The cluster arrangement similar that complex I, orientation not, which supports hypothesis evolved as prebuilt modules. active site includes a six-coordinate Ni,...

Abstract A [NiFe] hydrogenase (H 2 ase) is a proton‐coupled electron transfer enzyme that catalyses reversible H oxidation; however, its fundamental proton pathway remains unknown. Herein, we observed the protonation of Cys546‐SH and Glu34‐COOH near Ni–Fe site with high‐sensitivity infrared difference spectra by utilizing Ni‐C‐to‐Ni‐L Ni‐C‐to‐Ni‐SI photoconversions. Protonated in Ni‐L state was verified SH stretching frequency (2505 cm −1 ), whereas Cys546 deprotonated Ni‐C Ni‐SI states....

Many proteins, including heme proteins undergo three-dimensional domain swapping (3D-DS). The loop between E and F helices is converted to a helical structure in the myoglobin (Mb) 3D-DS dimer. However, relationship insertion Mb remains unclear. Here, we systematically investigated propensity of wild-type (WT) its variant which one three Ala residues were introduced into hinge region: G80A (K3AH2), G80A/H81A (K3A2H), G80A/H81A/H82A (K3A3). After heating monomer at 70 °C for 30 min, no dimers...

Protein‐based supramolecules require precise arrangement of building blocks. A regular‐triangle trimer (cp‐c555)3 has been constructed using an α‐helix‐inserted‐circular permutant (cp‐c555) Aquifex aeolicus cytochrome (cyt) c555, where the trimers may dissociate to monomers. In this study, we stabilized structure by constructing a cyclic three α‐helix‐linked cyt c555 molecules sortase‐mediated ligation (SML). Comparing SML sortase for six cp‐c555 variant trimers, with GGG at N‐terminus and...

Sperm whale myoglobin, an oxygen storage hemoprotein, was successfully reconstituted with the iron porphycene having two propionates, 2,7-diethyl-3,6,12,17-tetramethyl-13,16-bis(carboxyethyl)porphycenatoiron. The physicochemical properties and ligand bindings of myoglobin were investigated. ferric shows remarkable stability against acid denaturation only a low-spin characteristic in its EPR spectrum. Fe(III)/Fe(II) redox potential (−190 mV vs NHE) determined by spectroelectrochemical...

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTHydroperoxo−Copper(II) Complex Stabilized by N3S-Type Ligand Having a Phenyl ThioetherMasahito Kodera, Toshio Kita, Izumi Miura, Noritoshi Nakayama, Tomohisa Kawata, Koji Kano, and Shun HirotaView Author Information Department of Molecular Science Technology Doshisha University, Kyotanabe Kyoto 610-0321, Japan Chemistry Graduate School Science, Nagoya University Chikusa-ku, 464-01, Cite this: J. Am. Chem. Soc. 2001, 123, 31,...

The mechanism of dioxygen reduction catalyzed by cytochrome c oxidase, the terminal enzyme respiration chain aerobic organisms, has been investigated with time-resolved resonance Raman spectroscopy. Five oxygen isotope sensitive bands have identified for 16O2/18O2 intermediates at 571/544, 804/764, 356/342, 785/750, and 450/425 cm-1 in order appearance. first last ones, which assigned to FeIIIO2- FeIIIOH- stretching modes, respectively, are general consensus, but remaining three currently...