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41.
Photocurrent Generation through Charge‐Transfer Processes in Noncovalent Perylenediimide/DNA Complexes 下载免费PDF全文
Dr. Tadao Takada Misa Ido Akane Ashida Dr. Mitsunobu Nakamura Dr. Mamoru Fujitsuka Dr. Kiyohiko Kawai Prof. Tetsuro Majima Prof. Kazushige Yamana 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(18):6846-6851
The charge‐transfer process in noncovalent perylenediimide (PDI)/DNA complexes has been investigated by using nanosecond laser flash photolysis (LFP) and photocurrent measurements. The PDI/DNA complexes were prepared by inclusion of cationic PDI molecules into the artificial cavities created inside DNA. The LFP experiments showed that placement of the PDI chromophore at a specific site and included within the base stack of DNA led to the efficient generation of a charge‐separated state with a long lifetime by photoexcitation. When two PDI chromophores were separately placed at different positions in DNA, the yield of the charge‐separated state with a long lifetime was dependent upon the number of A–T base pairs between the PDIs, which was explained by electron hopping from one PDI to another. Photocurrent generation of the DNA‐modified electrodes with the complex was also dependent upon the arrangement of the PDI chromophores. A good correlation was obtained between observed charge separation and photocurrent generation on the PDI/DNA‐modified electrodes, which demonstrated the importance of the defined arrangement and assembly of organic chromophores in DNA for efficient charge separation and transfer in multichromophore arrays. 相似文献
42.
Let p be a prime, k an algebraically closed field ofcharacteristic p, and G a finite group with a Sylowp-Subgroup P. In this paper, we consider the property thatNG(P)/P is Abelian. We provide somenecessary or sufficient conditions NG(P)/P to be Abelian in term of thestructure of the group algebra kG as a k-algebra, in casethat G is p-nilpotent or of p-length 1. 相似文献
43.
Misa V. Jovanovic Edward R. Biehl Patrice De Meester Shirley S. C. Chu 《Journal of heterocyclic chemistry》1984,21(3):885-888
The structure of the titled compound, 4 , has been solved by x-ray analysis. One of the important structural features of 4 is that the 2′-nitrophenyl group is in the plane bisecting the phenothiazine ring which is in contrast to that of 10-(2′-pyrazyl)phenothiazine of 4′-nitro-10-phenylphenothiazine in which the 10-aryl group is perpendicular to the plane bisecting the phenothiazine ring. The structure of 4 is in agreement with its 1H and 13C nmr data which indicate that resonance interactions between the 2′-nitrophenyl group and the lone pair of electrons on N10 are hindered sterically by the 2′-nitro group. 相似文献
44.
Role of copper ion in bacterial copper amine oxidase: spectroscopic and crystallographic studies of metal-substituted enzymes 总被引:1,自引:0,他引:1
Kishishita S Okajima T Kim M Yamaguchi H Hirota S Suzuki S Kuroda S Tanizawa K Mure M 《Journal of the American Chemical Society》2003,125(4):1041-1055
The role of the active site Cu(2+) of phenylethylamine oxidase from Arthrobacter globiformis (AGAO) has been studied by substitution with other divalent cations, where we were able to remove >99.5% of Cu(2+) from the active site. The enzymes reconstituted with Co(2+) and Ni(2+) (Co- and Ni-AGAO) exhibited 2.2 and 0.9% activities, respectively, of the original Cu(2+)-enzyme (Cu-AGAO), but their K(m) values for amine substrate and dioxygen were comparable. X-ray crystal structures of the Co- and Ni-AGAO were solved at 2.0-1.8 A resolution. These structures revealed changes in the metal coordination environment when compared to that of Cu-AGAO. However, the hydrogen-bonding network around the active site involving metal-coordinating and noncoordinating water molecules was preserved. Upon anaerobic mixing of the Cu-, Co-, and Ni-AGAO with amine substrate, the 480 nm absorption band characteristic of the oxidized form of the topaquinone cofactor (TPQ(ox)) disappeared rapidly (< 6 ms), yielding the aminoresorcinol form of the reduced cofactor (TPQ(amr)). In contrast to the substrate-reduced Cu-AGAO, the semiquinone radical (TPQ(sq)) was not detected in Co- and Ni-AGAO. Further, in the latter, TPQ(amr) reacted reversibly with the product aldehyde to form a species with a lambda(max) at around 350 nm that was assigned as the neutral form of the product Schiff base (TPQ(pim)). Introduction of dioxygen to the substrate-reduced Co- and Ni-AGAO resulted in the formation of a TPQ-related intermediate absorbing at around 360 nm, which was assigned to the neutral iminoquinone form of the 2e(-)-oxidized cofactor (TPQ(imq)) and which decayed concomitantly with the generation of TPQ(ox). The rate of TPQ(imq) formation and its subsequent decay in Co- and Ni-AGAO was slow when compared to those of the corresponding reactions in Cu-AGAO. The low catalytic activities of the metal-substituted enzymes are due to the impaired efficiencies of the oxidative half-reaction in the catalytic cycle of amine oxidation. On the basis of these results, we propose that the native Cu(2+) ion has essential roles such as catalyzing the electron transfer between TPQ(amr) and dioxygen, in part by providing a binding site for 1e(-)- and 2e(-)-reduced dioxygen species to be efficiently protonated and released and also preventing the back reaction between the product aldehyde and TPQ(amr). 相似文献
45.
Improvement of Ligand Affinity and Thermodynamic Properties by NMR‐Based Evaluation of Local Dynamics and Surface Complementarity in the Receptor‐Bound State 下载免费PDF全文
Dr. Yumiko Mizukoshi Dr. Koh Takeuchi Misa Arutaki Dr. Yuji Tokunaga Takeshi Takizawa Dr. Hiroyuki Hanzawa Prof. Dr. Ichio Shimada 《Angewandte Chemie (International ed. in English)》2016,55(47):14606-14609
The thermodynamic properties of a ligand in the bound state affect its binding specificity. Strict binding specificity can be achieved by introducing multiple spatially defined interactions, such as hydrogen bonds and van der Waals interactions, into the ligand–receptor interface. These introduced interactions are characterized by restricted local dynamics and improved surface complementarity in the bound state. In this study, we experimentally evaluated the local dynamics and the surface complementarity of weak‐affinity ligands in the receptor‐bound state by forbidden coherence transfer analysis in free‐bound exchange systems (Ex‐FCT), using the interaction between a ligand, a myocyte‐enhancer factor 2A (MEF2A) docking peptide, and a receptor, p38α, as a model system. The Ex‐FCT analyses successfully provided information for the rational design of a ligand with higher affinity and preferable thermodynamic properties for p38α. 相似文献
46.
Rational control of enantioselectivity of lipase by site-directed mutagenesis based on the mechanism
Ema T Fujii T Ozaki M Korenaga T Sakai T 《Chemical communications (Cambridge, England)》2005,(37):4650-4651
The enantioselectivity of a Burkholderia cepacia lipase toward secondary alcohols could be both increased and decreased rationally by introducing only a single mutation on the basis of the mechanism proposed previously. 相似文献
47.
Patrice De Meester Shirley S. C. Chu Misa V. Jovanovic Edward R. Biehl 《Journal of heterocyclic chemistry》1986,23(2):337-341
Crystals of 5-phenylbarbituric acid, 2 , are monoclinic, space group C2/c. There are 8 molecules in the unit cell of dimensions a = 20.218(3), b = 7.477(1), c, = 12.443(2), β = 111.54° and V = 1749.6(4) Å3. Full-matrix least-squares refinement has reached R = 0.039. This is the first barbiturate reported to exist in the enol form in the solid state. There is extensive hydrogen bonding between adjacent molecules which gives rise to very dense crystals. The 13C-nmr spectroscopy shows that 2 exists in both enol and keto forms in DMSO solution. 相似文献
48.
We construct new integral standard generalized table algebras from parameters of projective geometries. The algebras are noncommutative, imprimitive, and six dimensional. 相似文献
49.
Akihide Hanaki Mitsugu Hirasaka Katsuhiro Uno 《Journal of Algebraic Combinatorics》2008,27(3):307-316
Through a study of the structure of the modular adjacency algebra over a field of positive characteristic p for a scheme of prime order p and utilizing the fact that every scheme of prime order is commutative, we show that every association scheme of prime square
order having a non-trivial thin closed subset is commutative.
The second author was supported by Korea Research Foundation Grant (KRF-2006-003-00008). 相似文献
50.
Akihide Hanaki 《Journal of Combinatorial Theory, Series A》2008,115(2):226-236
We give a definition of nilpotent association schemes as a generalization of nilpotent groups and investigate their basic properties. Moreover, for a group-like scheme, we characterize the nilpotency by its character products. 相似文献