Takashi Hayashi

The reconstitution of myoglobin with an artificially created prosthetic group is a unique method for introducing a new chemical function into the protein. Particularly, the modification of two heme-propionates gives us an effective binding domain or binding site on the protein surface. This Account traces the design and construction of the highly ordered binding domain around the entrance of the heme pocket. The discussion includes the protein-small molecule or protein-protein recognition, elect

In the respiratory system, electron carriers such as ubiqui-none and cytochrome c play an important role in the electron transfer (ET) reaction between oxidoreductases embedded in the mitochondrial membrane. This review focuses on a strategy for constructing porphyrin–electron acceptor pairs via specific interactions and the evaluation of ET in these systems. Particularly, the molecular recognition of ubiqui-none analogues by porphyrin host molecules and the mimicking of protein–protein complexa

Ferroelectric BaTiO 3 thin films were prepared on Pt(111)/ SiO 2 /Si(100) substrates at 650° C by the sol-gel method. Film thickness could be varied by repeating a dip coating/heating cycle. The texture of the BaTiO 3 thin films became more dense and homogeneous when the film thickness increased. The crystalline thin films showed microstructure with grains as small as 20–30 nm. The dielectric properties could be measured for films thicker than 0.25 µ m. With increasing film thickness, the dielec

Myoglobin will be a good scaffold for engineering a function into proteins. To modulate the physiological function of myoglobin, almost all approaches have been demonstrated by site-directed mutagenesis, however, there are few studies which show a significant improvement in the function. In contrast, we focused on the replacement of heme in the protein with an artificial prosthetic group. Recently, we prepared a novel myoglobin reconstituted with an iron porphycene as a structural isomer of meso

The diiron carbonyl cluster is held by a native CXXC motif, which includes Cys14 and Cys17, in the cytochrome c sequence. It is found that the diiron carbonyl complex works well as a catalyst for H(2) evolution. It has a TON of ∼80 over 2 h at pH 4.7 in the presence of a Ru-photosensitizer and ascorbate as a sacrificial reagent in aqueous media.

Peroxidase activity of a myoglobin reconstituted with a chemically modified heme 1 is reported. The heme 1 bearing a total of eight carboxylates bound to the terminal of propionate side chains is incorporated into apomyoglobin from horse heart to obtain a new reconstituted myoglobin, rMb(1), with a unique binding domain structure. The UV−vis, CD, and NMR spectra of rMb(1) are comparable with those of native myoglobin, nMb. The mixing of rMb(1) with hydrogen peroxide yields a peroxidase compound

The incorporation of an artificially created metal complex into an apomyoglobin is one of the attractive methods in a series of hemoprotein modifications. Single crystals of sperm whale myoglobin reconstituted with 13,16-dicarboxyethyl-2,7-diethyl-3,6,12,17-tetramethylporphycenatoiron(III) were obtained in the imidazole buffer, and the 3D structure with a 2.25-A resolution indicates that the iron porphycene, a structural isomer of hemin, is located in the normal position of the heme pocket. Furt

Cobalt(III) porphycenes, structural isomers of cobalt(III) porphyrins, catalyze the addition of alcohols to vinyl ethers in a toluene−dioxane solution containing alcohol and Et3N as well as the autoxidation of the resultant metal-bound adduct; this produces two acetals, namely, those of β-formylacetaldehyde and β-hydroxyacetaldehyde, with a total turnover number of 34−77 after 21 h at 20 °C. Under identical reaction conditions, analogous cobalt(III) porphyrins were found to undergo rapid decompo

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSpecific molecular recognition via multipoint hydrogen bonding ubiquinone analogs - porphyrin having four convergent hydroxyl groups pairingTakashi Hayashi, Takashi Miyahara, Naomichi Hashizume, and Hisanobu OgoshiCite this: J. Am. Chem. Soc. 1993, 115, 5, 2049–2051Publication Date (Print):March 1, 1993Publication History Published online1 May 2002Published inissue 1 March 1993https://pubs.acs.org/doi/10.1021/ja00058a068https://doi.org/10.1021/ja00058a

meso-α,α,α,α-Tetrakis(2-hydroxy-1-naphthyl)porphyrin (1) and 5,15-cis-bis(2-hydroxy-1-naphthyl)-10,20-diphenylporphyrin (2) were prepared as receptors for ubiquinone analogues. UV−vis, IR, NMR, and X-ray crystal data reveal that these porphyrins bind a series of quinones with a cofacial structure linked by hydrogen bonds. The binding constants of 1 for quinones increase with the number of MeO substituents bound to a quinone ring. Compared to 2,5-dimethoxy-p-benzoquinone, 2,3-dimethoxy-p-benzoqui

Abstract The incorporation of a Rh complex with a maleimide moiety into the cavity of the nitrobindin β‐barrel scaffold by a covalent linkage at the 96‐position (Cys) provides a hybrid biocatalyst that promotes the polymerization of phenylacetylene. The appropriate structural optimization of the cavity by mutagenesis enhances the stereoselectivity of the polymer with a trans content of 82 % at 25 °C and pH 8.0. The X‐ray crystal structure of one of the hybrid biocatalysts at a resolution of 2.0

Abstract H64D myoglobin mutant was reconstituted with two different types of synthetic hemes that have aromatic rings and a carboxylate‐based cluster attached to the terminus of one or both of the heme‐propionate moieties, thereby forming a “single‐winged cofactor” and “double‐winged cofactor,” respectively. The reconstituted mutant myoglobins have smaller K m values with respect to 2‐methoxyphenol oxidation activity relative to the parent mutant with native heme. This suggests that the attached

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDynamic molecular recognition in a multifunctional porphyrin and a ubiquinone analogTakashi Hayashi, Tomohito Asai, Hirohisa Hokazono, and Hisanobu OgoshiCite this: J. Am. Chem. Soc. 1993, 115, 25, 12210–12211Publication Date (Print):December 1, 1993Publication History Published online1 May 2002Published inissue 1 December 1993https://doi.org/10.1021/ja00078a088RIGHTS & PERMISSIONSArticle Views241Altmetric-Citations45LEARN ABOUT THESE METRICSArticle Vi