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11.
Imabayashi S Mita T Kakiuchi T 《Langmuir : the ACS journal of surfaces and colloids》2005,21(6):2474-2479
The effect of charge-inverting modification of single surface lysine residue on the electron transfer (ET) reaction of horse heart cytochrome c (cyt c) is examined for 12 different types of mono-4-chloro-2,5-dinitrobenzoic acid substituted cyt c (mCDNPc) adsorbed on a Au(111) electrode modified with a self-assembled monolayer (SAM) of 7-mercapto-heptanoic acid (MHA). A negative shift in the redox potential by 10-35 mV as compared to that of native cyt c and a monolayer coverage in the range of 13-17 pmol cm(-2) are observed for electroactive mCDNPc's. The magnitude of the decrease in the ET rate constant (k(et)) of mCDNPc's compared with that of native cyt c depends on the position of the CDNP substitution. For mCDNPc's in which the modified lysine residue is outside of the interaction domain of cyt c with the SAM, the ratio of the k(et) of mCDNPc to that of native cyt c is correlated to the change in the dipole moment vector of cyt c due to the CDNP modification. This correlation suggests that the dipole moment of cyt c determines its orientation of adsorption on the SAM of MHA and significantly affects the rate of the ET. The CDNP modification of lysine residues at the interaction domain significantly decreases the rate, demonstrating the importance of the local charge environment in determining the rate of ET. 相似文献
12.
S. Nakajima H. Hayashi K. OHSHIMA K. Yamazaki Y. Kubo N. Samejima Y. Kakiuchi Y. Shindoh H. Koshimizu I. Sakata H. Yamauchi 《Photochemistry and photobiology》1987,46(5):783-788
Abstract Mono-DPTA-ethyleneglycol-Ga-deuteroporphyrin (MDEGD) was synthesized, by coordinating non-radioactive Ga in the porphyrin ring and connecting DTPA (diethylene-triamine-N,N,N,N,N,-pentaacetic acid) to its side chain. By labeling with 111In , chemicals for scintigraphy were developed. They were applied to Syrian golden hamsters with implanted pancreatic gland cancers and C57-black mice with Lewis lung cancer to enable tumor imaging and biodistribution examination. A comparative study was also conducted with [67 Ga]citrate. In the resultant data, [111 In]MDEGD showed larger tumor/lung, tumor/kidney and tumor/blood ratio with [67 Ga]citrate. The affinity of [n In]MDEGD in inflammatory tissue was much lower than that of 67 Ga citrate. [111 In]MDEGD lost its photosensitivity. 相似文献
13.
Ogata H Mizoguchi Y Mizuno N Miki K Adachi S Yasuoka N Yagi T Yamauchi O Hirota S Higuchi Y 《Journal of the American Chemical Society》2002,124(39):11628-11635
The carbon monoxide complex of [NiFe]hydrogenase from Desulfovibrio vulgaris Miyazaki F has been characterized by X-ray crystallography and absorption and resonance Raman spectroscopy. Nine crystal structures of the [NiFe]hydrogenase in the CO-bound and CO-liberated forms were determined at 1.2-1.4 A resolution. The exogenously added CO was assigned to be bound to the Ni atom at the Ni-Fe active site. The CO was not replaced with H(2) in the dark at 100 K, but was liberated by illumination with a strong white light. The Ni-C distances and Ni-C-O angles were about 1.77 A and 160 degrees, respectively, except for one case (1.72 A and 135 degrees ), in which an additional electron density peak between the CO and Sgamma(Cys546) was recognized. Distinct changes were observed in the electron density distribution of the Ni and Sgamma(Cys546) atoms between the CO-bound and CO-liberated structures for all the crystals tested. The novel structural features found near the Ni and Sgamma(Cys546) atoms suggest that these two atoms at the Ni-Fe active site play a role during the initial H(2)-binding process. Anaerobic addition of CO to dithionite-reduced [NiFe]hydrogenase led to a new absorption band at about 470 nm ( approximately 3000 M(-1)cm(-1)). Resonance Raman spectra (excitation at 476.5 nm) of the CO complex revealed CO-isotope-sensitive bands at 375/393 and 430 cm(-1) (368 and 413 cm(-1) for (13)C(18)O). The frequencies and relative intensities of the CO-related Raman bands indicated that the exogenous CO is bound to the Ni atom with a bent Ni-C-O structure in solution, in agreement with the refined structure determined by X-ray crystallography. 相似文献
14.
Kakiuchi K Okada H Kanehisa N Kai Y Kurosawa H 《The Journal of organic chemistry》1996,61(9):2972-2979
Acid-catalyzed rearrangement of 5-cyclopentylidenecyclooctanone derivatives 9a-c was examined to obtain polyspiropolyquinanes 11a-c, considered to have a unique helical structure, through cascade rearrangement pathways consisting of continuous transannular cyclization followed by successive 1,2-alkyl shifts. The substrates were prepared easily by use of the Wittig or McMurry reaction. Reaction of the 5-cyclopentylidenecyclooctanone (9a) with acid gave the expected dispirotriquinane ketone 11a in high yield. The precise mechanism was elucidated by a deuterium-labeling experiment. In the case of the ketone 9b, having another spiroannulated cyclopentane ring attached on 9a, the trispirotetraquiane 11b was not obtained but the bis-propellane-type tetrahydrofuran 25 was produced exclusively. The 5-(5'-cyclopentylidenecyclooctylidene)cyclooctanone (9c) afforded the polycyclic compounds 27-31, depending on the acid used, instead of the desired tetraspiropentaquinane 11c. The structures of the products were determined by NMR spectral data including 2D (13)C INADEQUATE spectra and X-ray crystallographic analyses. The unexpected rearrangement pathways are also discussed. 相似文献
15.
16.
Masao Tomoi Noriyuki Yanai Satoshi Shiiki Hiroshi Kakiuchi 《Journal of polymer science. Part A, Polymer chemistry》1984,22(4):911-926
Polymer-supported crown ethers were prepared from chloromethylated or ω-bromoalkylated polystyrene resins and hydroxymethylbenzo-18-crown-6 and 15- or 18-membered monoazacrown ethers. Effects of the cavity size of crown ethers, the degree of crosslinking, the degree of ring substitution, particle size, spacer chains, and solvents on the activity of the polymer-supported crown ethers in the reaction of 1-chloro- or 1-bromo-octane with aqueous NaI or KI were investigated and mechanisms of the reaction were discussed in terms of mass transfer, intraparticle diffusion, and intrinsic reactivity. 相似文献
17.
Ishii Y Iwahama T Sakaguchi S Nakayama K Nishiyama Y 《The Journal of organic chemistry》1996,61(14):4520-4526
A novel class of catalysts for alkane oxidation with molecular oxygen was examined. N-Hydroxyphthalimide (NHPI) combined with Co(acac)(n)() (n = 2 or 3) was found to be an efficient catalytic system for the aerobic oxidation of cycloalkanes and alkylbenzenes under mild conditions. Cycloalkanes were successfully oxidized with molecular oxygen in the presence of a catalytic amount of NHPI and Co(acac)(2) in acetic acid at 100 degrees C to give the corresponding cycloalkanones and dicarboxylic acids. Alkylbenzenes were also oxidized with dioxygen using this catalytic system. For example, toluene was converted into benzoic acid in excellent yield under these conditions. Ethyl- and butylbenzenes were selectively oxidized at their alpha-positions to form the corresponding ketones, acetophenone, and 1-phenyl-1-butanone, respectively, in good yields. A key intermediate in this oxidation is believed to be the phthalimide N-oxyl radical generated from NHPI and molecular oxygen using a Co(II) species. The isotope effect (k(H)/k(D)) in the oxidation of ethylbenzene and ethylbenzene-d(10) with dioxygen using NHPI/Co(acac)(2) was 3.8. 相似文献
18.
1,3,5-Trihydroxyisocyanuric acid (THICA), which serves as an efficient radical-producing catalyst from hydrocarbons, was successfully prepared by two methods. The reaction of O-benzylhydroxyamine with phenyl chloroformate gave formbenzyloxycarbamic acid phenyl ester of which subsequent treatment with dimethylaminopyridine (DMAP) produced 1,3,5-tribenzyloxyisocyanurate leading to THICA by hydrogenation with H2 on Pd/C. The other method involved the direct synthesis of 1,3,5-tribenzyloxyisocyanurate from O-benzylhydroxyamine and diphenyl carbonate. The aerobic oxidation of p-methylanisole catalyzed using THICA as a key catalyst afforded p-anisic acid in almost quantitative yield (>99%). 相似文献
19.
A theoretical analysis of the current-potential curves for facilitated ion transfer across an oil/water interface is presented for the case where two complex species having an ion-to-ligand ratio of 1:1 and 1:2 are allowed to exist in the oil phase. Cyclic voltammograms are calculated numerically by using a finite difference method assuming that the ion transfer is reversible and the complex formation equilibria are maintained throughout the oil phase. When the ligand concentration in the oil phase is much smaller than the ion concentration in the aqueous phase and the former limits the ion-transfer current, two well separated peaks may develop even under the assumption of equilibrium conditions for the complex formation. The shape of the voltammogram is determined primarily by the ratio of the two reduced stability constants: b1 = K1bcLO and b2 = K1K2(bcOL)2, where K1 and K2 are the stability constants for 1:1 and 1:2 complexes in the oil phase and bcOL the ligand concentration in the bulk of the oil phase. The degree of peak separation thus depends not only on K2/K1 but also on bcOL. A method for estimating the two stability constants from the voltammograms is proposed. 相似文献
20.
Kakiuchi F Kan S Igi K Chatani N Murai S 《Journal of the American Chemical Society》2003,125(7):1698-1699
The ruthenium-catalyzed reaction of aromatic ketones with arylboronic acid esters (arylboronates) gave the ortho arylation product. For this coupling reaction, a RuH2(CO)(PPh3)3 complex exhibited the highest catalytic activity among the complexes screened. Several aromatic ketones, for example, acetophenones, acetonaphthone, alpha-tetralone, and benzosuberone, can be used in this coupling reaction. A variety of arylboronates containing electron-donating (OMe and NMe2) and -withdrawing (F and CF3) groups were found to react with aromatic ketones to give the corresponding aylation products. The corresponding arylboronic acids could be used in this coupling reaction, but the yields were slightly lower, as compared to those of the reaction using the corresponding arylboronates. 相似文献