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1.
Lars Lauterbach Hongxin Wang Marius Horch Leland B. Gee Yoshitaka Yoda Yoshihito Tanaka Ingo Zebger Oliver Lenz Stephen P. Cramer 《Chemical science》2015,6(2):1055-1060
Hydrogenases are complex metalloenzymes that catalyze the reversible splitting of molecular hydrogen into protons and electrons essentially without overpotential. The NAD+-reducing soluble hydrogenase (SH) from Ralstonia eutropha is capable of H2 conversion even in the presence of usually toxic dioxygen. The molecular details of the underlying reactions are largely unknown, mainly because of limited knowledge of the structure and function of the various metal cofactors present in the enzyme. Here, all iron-containing cofactors of the SH were investigated by 57Fe specific nuclear resonance vibrational spectroscopy (NRVS). Our data provide experimental evidence for one [2Fe2S] center and four [4Fe4S] clusters, which is consistent with the amino acid sequence composition. Only the [2Fe2S] cluster and one of the four [4Fe4S] clusters were reduced upon incubation of the SH with NADH. This finding explains the discrepancy between the large number of FeS clusters and the small amount of FeS cluster-related signals as detected by electron paramagnetic resonance spectroscopic analysis of several NAD+-reducing hydrogenases. For the first time, Fe–CO and Fe–CN modes derived from the [NiFe] active site could be distinguished by NRVS through selective 13C labeling of the CO ligand. This strategy also revealed the molecular coordinates that dominate the individual Fe–CO modes. The present approach explores the complex vibrational signature of the Fe–S clusters and the hydrogenase active site, thereby showing that NRVS represents a powerful tool for the elucidation of complex biocatalysts containing multiple cofactors. 相似文献
2.
Dr. Ziqian Xue Dr. Jia-Jia Zheng Dr. Yusuke Nishiyama Dr. Ming-Shui Yao Dr. Yoshitaka Aoyama Zeyu Fan Dr. Ping Wang Prof. Takashi Kajiwara Prof. Yoshiki Kubota Prof. Satoshi Horike Prof. Ken-ichi Otake Prof. Susumu Kitagawa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(2):e202215234
Exploring new porous coordination polymers (PCPs) that have tunable structure and conductivity is attractive but remains challenging. Herein, fine pore structure engineering by ligand conformation control of naphthalene diimide (NDI)-based semiconducting PCPs with π stacking-dependent conductivity tunability is achieved. The π stacking distances and ligand conformation in these isoreticular PCPs were modulated by employing metal centers with different coordination geometries. As a result, three conjugated PCPs (Co−pyNDI, Ni−pyNDI, and Zn−pyNDI) with varying pore structure and conductivity were obtained. Their crystal structures were determined by three-dimensional electron diffraction. The through-space charge transfer and tunable pore structure in these PCPs result in modulated selectivity and sensitivity in gas sensing. Zn−pyNDI can serve as a room-temperature operable chemiresistive sensor selective to acetone. 相似文献
3.
Dr. Masahito Yoshida Yoshitaka Ishida Kenta Adachi Hayato Murase Dr. Hiroshi Nakagawa Prof.Dr. Takayuki Doi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(50):18417-18430
The solid‐phase combinatorial synthesis of cyclodepsipeptide destruxin E has been demonstrated. The combinatorial synthesis of cyclization precursors 8 was achieved by using a split and pool method on SynPhase Lanterns. The products were successfully macrolactonized in parallel in the solution phase by using 2‐methyl‐6‐nitrobenzoic anhydride and 4‐(dimethylamino)pyridine N‐oxide to afford macrolactones 9 , and the subsequent formation of an epoxide in the side chain gave 18 member destruxin E analogues 6 . Biological evaluation of analogues 6 indicated that the N‐MeAla residue was crucial to the induction of morphological changes in osteoclast‐like multinuclear cells (OCLs). Based on structure–activity relationships, azido‐containing analogues 15 were then designed for use as a molecular probe. The synthesis and biological evaluation of analogues 15 revealed that 15 b , in which the Ile residue was replaced with a Lys(N3) residue, induced morphological changes in OCLs at a sufficient concentration, and modification around the Ile residue would be tolerated for attachment of a chemical tag toward the target identification of destruxin E ( 1 ). 相似文献
4.
In this paper, we introduce the two-dimensional continuous wavelet transform for the automated strain analysis of the moiré
interference fringe pattern. The Fourier transform method has been widely used for automated analysis of an optical interference
fringe pattern. However, this method is hardly applicable to the analysis of the fringe pattern, which includes large displacement
range or discontinuities. We show the advantages of the wavelet transform method by applying it to experimental results on
composite laminates. 相似文献
5.
6.
Yoshitaka Yoda Yasuhiko Imai Hisao Kobayashi Syunji Goto Kunikazu Takeshita Makoto Seto 《Hyperfine Interactions》2012,206(1-3):83-86
An Upgrade of the nuclear resonant scattering beamline, BL09XU in SPring-8 has been conducted. A liquid nitrogen cooled high-heat load monochromator was installed and a 2nd experimental hutch was constructed. The instruments installed in the hutch allow for a variety of sample conditions. Newly developed high-resolution monochromators with better stability including the back scattering geometry monochromator have opened up the easy access to more isotopes and more precise measurements. 相似文献
7.
Saeed Kamali Hongxin Wang Devrani Mitra Hideaki Ogata Wolfgang Lubitz Brian C. Manor Thomas B. Rauchfuss Deborah Byrne Violaine Bonnefoy Francis E. Jenney Michael W. W. Adams Yoshitaka Yoda Ercan Alp Jiyong Zhao Stephen P. Cramer 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2013,125(2):752-756
8.
In the presence of a catalytic amount of ammonium chiral borate salt, asymmetric Friedel-Crafts alkylation of indoles with α,β-disubstituted enals proceeded to give the corresponding 1,4-addition products with moderate enantioselectivities. 相似文献
9.
10.