Application of Nafion／Cobalt Hexacyanoferrate Chemically Modified Electrodes for the Determination of Electroinactive Cations by Ion Chromatography

Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｉｏｎｃｈｒｏｍａｔｏｇｒａｐｈｙ (ＩＣ)ｈａｓｂｅｅｎｒｅｃｏｇｎｉｚｅｄａｓａｕｓｅｆｕｌｍｅｔｈｏｄｆｏｒｔｈｅｓｅｐａｒａｔｉｏｎｏｆｉｎｏｒｇａｎｉｃａｎｉｏｎｓａｎｄｃａｔｉｏｎｓｓｉｎｃｅｉｔｓｉｎｔｒｏｄｕｃｔｉｏｎｂｙＳｍａｌｌｅｔａｌ .ｉｎ 1975 .1ＡｓｉｇｎｉｆｉｃａｎｔｔｒｅｎｄｉｎｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆＩＣｍｅｔｈｏｄｉｓｓｅａｒｃｈｆｏｒｓｅｎｓｉｔｉｖｅａｎｄｕｎｉｖｅｒｓａｌｄｅｔｅｃｔｉｏｎｍｅｔｈｏｄｓ .Ｔｈｅｍａｉｎｄｅｔ…     

Identification of the Flavone in the Flower Bud of Panax Quinquefolium and Its Content Determination in the Different Parts

ＰａｎａｘｑｕｉｎｑｕｅｆｏｌｉｕｍＬ .ｂｅｌｏｎｇｓｔｏｔｈｅＰａｎａｘｇｅｎｕｓｏｆｔｈｅＡｒａｌｉａｃｅａｅ .ＩｔｏｒｉｇｉｎａｔｅｓｉｎＡｍｅｒｉｃａａｎｄＣａｎａｄａ .Ｉｔｓｒｏｏｔｓ ,ａｆａｍｏｕｓａｎｄｅｘｐｅｎｓｉｖｅｔｒａｄｉｔｉｏｎａｌＣｈｉｎｅｓｅｍｅｄｉｃｉｎａｌｍａｔｅｒｉ ａｌ,ｈａｖｅｂｅｅｎｓｔｕｄｉｅｄｃｏｎｔｉｎｕａｌｌｙｓｉｎｃｅｉｔｓｓｕｃｃｅｓｓｆｕｌｃｕｌｔｉｖａｔｉｏｎｉｎＣｈｉｎａｉｎｔｈｅ 1 970’ｓ .Ｉｎｒｅ ｃｅｎｔｙｅａｒｓｔｈｅｄｅｖｅｌｏｐ…     

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ＣｈｉｎｅｓｅＪｏｕｒｎａｌｏｆＣｈｒｏｍａｔｏｇｒａｐｈｙ,ａｊｏｕｒｎａｌｕｎｄｅｒｔａｋｅｎｂｙＣｈｉｎｅｓｅＣｈｅｍｉｃａｌＳｏｃｉｅｔｙ,ｐｕｂｌｉｓｈｅｓａｒｔｉｃｌｅｓｉｎＣｈｉｎｅｓｅａｎｄｉｎＥｎｇｌｉｓｈｏｎａｌｌａｓｐｅｃｔｓｏｆｃｈｒｏｍａｔｏｇｒａｐｈｙ .Ｔｏｐｉｃｓｉｎｃｌｕｄｅｎｅｗｏｒｉｍｐｒｏｖｅｄａｎａｌｙｔｉｃａｌａｎｄｐｒｅｐａｒａｔｉｖｅｍｅｔｈｏｄｓ,ｄｅｖｅｌｏｐｍｅｎｔｏｆｔｈｅｏｒｉｅｓ,ａｎｄｉｎｎｏｖａｔｉｖｅａｐｐｌｉｃａｔｉｏｎｓｏｆｃｈｒｏ…     

Characterization and Dehydrogenation Activity of SBA-15 and HMS Supported Chromia Catalysts

ＩｎｔｒｏｄｕｃｔｉｏｎＥｎｏｒｍｏｕｓｓｔｕｄｙｈａｓｂｅｅｎｄｅｖｏｔｅｄｔｏＭ4 1Ｓ ,ｔｈｅｆｉｒｓｔｆａｍｉｌｙｏｆｍｅｓｏｐｏｒｏｕｓｍｏｌｅｃｕｌａｒｓｉｅｖｅｓｒｅｐｏｒｔｅｄｉｎ1992 ,1,2 ｉｎｃｌｕｄｉｎｇｔｈｅｉｒｍｏｄｉｆｉｃａｔｉｏｎｓａｎｄａｐｐｌｉｃａｔｉｏｎｓｉｎｃａｔａｌｙｓｉｓ .Ｔｈｅａｔｔｒａｃｔｉｖｅｐｒｏｐｅｒｔｉｅｓｏｆｔｈｅｓｅｍａｔｅｒｉａｌｓａｒｅｔｈｅｉｒｈｉｇｈｓｐｅｃｉｆｉｃｓｕｒｆａｃｅａｒｅａ (>10 0 0ｍ2 /ｇ) ,ｗｅｌｌ ｄｅ ｆｉｎｅｄｓｔｒ…     

Synthesis of 7-Ethyl-10-hydroxycamptothecin and Proposed Reaction Mechanism

20 (Ｓ) Ｃａｍｐｔｏｔｈｅｃｉｎ(ＣＰＴ) ,ａｃｙｔｏｔｏｘｉｃａｌｋａｌｏｉｄｗｉｔｈｅｆｆｉｃａｃｙｉｎａｎｉｍａｌｔｕｍｏｒｍｏｄｅｌｓ ,ｗａｓｆｉｒｓｔｉｓｏｌａｔｅｄａｎｄｃｈａｒａｃｔｅｒｉｚｅｄｂｙＷａｌｌａｎｄｃｏｗｏｒｋｅｒｓｉｎ 1 96 6ｆｒｏｍｌｅａｖｅｓａｎｄｂａｒｋｓｏｆＣａｍｐｔｏｔｈｅｃａａｃｕｍｉｎａｔａ(ｆａｍｉｌｙＮｙｓｓａｃｅａｅ ,ａｐｌａｎｔｎａｔｉｖｅｔｏＣｈｉｎａ) [1] .Ｔｈｅｍｏｌｅｃｕｌｅｈａｓａｐｅｎｔａｃｙｃｌｉｃｓｔｒｕｃｔｕｒｅｃｏｎｓｉｓｔｉｎ…     

Synthesis and Characterization of Poly(isoprene-b-butyl methacrylate) Block Copolymer in the Presence of Rare Earth Catalyst

ＩｎｔｒｏｄｕｃｔｉｏｎＢｌｏｃｋｃｏｐｏｌｙｍｅｒｉｚａｔｉｏｎｓｏｆｏｌｅｆｉｎｗｉｔｈａｃｒｙｌａｔｅｓｈａｖｅａｒｏｕｓｅｄｍｏｒｅａｎｄｍｏｒｅａｔｅｎｔｉｏｎｓｓｉｎｃｅｔｈｅｓｅｐｒｏｃｅｓｓｅｓｅｎｄｏｗｐｏｌｙｍｅｒｉｃｍａｔｅｒｉ...     

Synthesizing β-Chiral Carbon Alkanoic Acids and Alcohols via(-)-Bornane-10,2-crotonoylsultam

ＩｎｔｒｏｄｕｃｔｉｏｎＣｈｉｒａｌｍｅｔｈｙｌｍｏｉｅｔｙｉｓｇｅｎｅｒａｌｙｉｎｎａｔｕｒａｌｐｒｏｄｕｃｔｓａｎｄｍｅｄｉｃｉｎｅｓ［１］，ｗｈｉｌｅｏｐｔｉｃａｌｙａｃｔｉｖｅａｃｉｄｓａｎｄａｌｃｏｈｏｌｓａｒｅｕｓｕａｌｙｕｓｅｄａｓｉｎ...     

SYNTHESIS OF NaA ZEOLITE MEMBRANE FROM CLEAR SOLUTION AND ITS GAS PERMEATION PROPERTIES

Ｔｈｅｕｓｅｏｆｚｅｏｌｉｔｅｍｅｍｂｒａｎｅｓｉｎｓｅｐａｒａｔｉｏｎｏｒｃｏｍｂｉｎｅｄｒｅａｃｔｉｏｎａｎｄｓｅｐａｒａｔｉｏｎｐｒｏｃｅｓｅｓｉｓｖｅｒｙａｔｒａｃｔｉｖｅ．Ａｄｖａｎｔａｇｅｓｏｆｕｓｉｎｇｓｕｃｈａｔｙｐｅｏｆｍｅｍｂｒａ...     

Microcalorimetric Character of Inhibition of Salicylaldehyde Glucosamine Schiff Base SG on Bacterial Metabolism

ＩｎｔｒｏｄｕｃｔｉｏｎＳｉｎｃｅＳｃｈｉｆｂａｓｅａｎｄｉｔｓｍｅｔａｌｃｏｍｐｌｅｘｅｓａｒｅｏｆａｎｔｉｂａｃｔｅｒｉａｌａｎｄａｎｔｉｃａｎｃｅｒｂｉｏａｃｔｉｖｉｔｉｅｓ，ｔｈｅｙｈａｖｅｂｅｅｎａｒｅｓｅａｒｃｈｓｕｂｊｅｃｔｏｆｍｕｃｈ...     

Synthesis,Structure,Characterization and Electrochemistry of a New Dinuclear W(0)-complex 〔Et_4N〕_2〔W_2(CO)_8(SCH_2COOMe)_2〕

１ＩＮＴＲＯＤＵＣＴＩＯＮＲｅｃｅｎｔｌｙ,ｔｈｅｃｈｅｍｉｓｔｒｙｏｆｃｏｍｐｌｅｘｅｓｃｏｎｔａｉｎｉｎｇｌｏｗ ｖａｌｅｎｃｅｍｅｔａｌａｔｏｍｓｈａｓｉｎｃｒｅａｓ ｉｎｇｌｙａｔｒａｃｔｅｄｔｈｅａｔｅｎｔｉｏｎｆｒｏｍｃｈｅｍｉｓｔｓａｎ...     

Synergistic Effects of Metals in a Promising RuII−PtII Assembly for a Combined Anticancer Approach: Theoretical Exploration of the Photophysical Properties

Ru^II?Pt^II complexes are a class of bioactive molecules of interest as anticancer agents that combine a light‐absorbing chromophore with a cisplatin‐like unit. The results of a DFT and TDDFT investigation of a Ru^II complex and its conjugate with a cis‐PtCl₂ moiety reveal that a synergistic effect of the metals makes the assembly a promising multitarget anticancer drug. Inspection of type I and type II photoreactions and spin–orbit coupling computations reveals that the cis‐PtCl₂ moiety improves the photophysical properties of the Ru^II chromophore, ensuring efficient singlet oxygen generation and making the assembly suitable for photodynamic therapy. At the same time, the Ru^II chromophore promotes a new alternative activation mechanism of the Pt^II ligand via a triplet metal‐to‐ligand charge transfer (³M LCT) state, before reaching the biological target. The importance of the supramolecular architecture is accurately derived, opening interesting new perspectives on the use of bimetallic Ru^II?Pt^II assemblies in a combined anticancer approach.     

Multiwalled carbon nanotube-doxorubicin supramolecular complexes for cancer therapeutics

Multiwalled carbon nanotube aqueous dispersions using block copolymers are able to form supramolecular complexes with the aromatic chromophore and anticancer agent doxorubicin via pi-pi stacking and enhance its cytotoxic activity.     

Rational design of a supra C-1027: kinetically stabilized analogue of the antitumor enediyne chromoprotein

C-1027, an extremely potent antitumor agent, is composed of a highly reactive chromophore and an apoprotein. While the chromophore causes DNA cleavage, the apoprotein functions as its carrier. Despite these ideal properties as an anticancer agent, C-1027 slowly self-decomposes through chromophore-mediated abstraction of hydrogens from the apoprotein. In this paper, we report the design and preparation of an engineered C-1027 apoprotein that decelerates this self-decomposition pathway. Our design is based on the kinetic isotope effect, and deuterium is incorporated instead of protium into the hydrogen-abstraction site. The deuterated supra C-1027 was found to have a 4-fold longer lifetime than the natural C-1027.     

Synthetic Study Towards the Total Synthesis of Neocarzinostatin Chromophore

The chromophores of enediyne chromoprotein anticancer antibiotics have attracted a lot of efforts towards the total synthesis. Very recently, Myers group^[1] reported the first synthesis of neocarzinostatin chromophore 1. The key point of our approach for the total synthesis of this compound is to construct the highly strained and unstable bicyclic[7.3.0]epoxyenediyne core at the late stage of synthesis using an intramolecular acetylide aldehyde ring closure. The proposed approach is illustrated retrosynthetically as follows (Scheme).     

米托蒽醌与B-DNA相互作用的分子模拟

针对嵌插型抗癌药物米托蒽醌(mitoxantrone,MTX)同B-DNA间作用模式的争议,采用分子模拟方法研究了米托蒽醌分子与B-DNA分子的相互作用.结果表明:米托蒽醌分子插入到B-DNA中有大小沟选择性及碱基对特异性,更倾向从小沟方向插入到DNA分子中;对5'-CG碱基对有特异性识别.通过详细能量项的分析,揭示了米托蒽醌插入DNA分子的驱动力及对碱基的特异性识别作用主要是空间相互作用特别是静电相互作用.在最佳作用位点复合物的构象分析则表明蒽醌环只有一部分插入碱基对中,侧链在小沟中延磷酸基骨架以3'-5'方向伸展,并通过静电作用进一步增强米托蒽醌与B-DNA的结合.     

Common pathway for the red chromophore formation in fluorescent proteins and chromoproteins

The mechanism of the chromophore maturation in members of the green fluorescent protein (GFP) family such as DsRed and other red fluorescent and chromoproteins was analyzed. The analysis indicates that the red chromophore results from a chemical transformation of the protonated form of the GFP-like chromophore, not from the anionic form, which appears to be a dead-end product. The data suggest a rational strategy to achieve the complete red chromophore maturation utilizing substitutions to favor the formation of the neutral phenol in GFP-like chromophore. Our approach to detect the neutral chromophore form expands the application of fluorescent timer proteins to faster promoter activities and more spectrally distinguishable fluorescent colors. Light sensitivity found in the DsRed neutral form, resulting in its instant transformation to the mature red chromophore, could be exploited to accelerate the fluorescence acquisition.     

The role of the protein matrix in green fluorescent protein fluorescence

In the ground state of the highly conjugated green fluorescent protein (GFP), the chromophore should be planar. However, numerous crystal structures of GFP and GFP-like proteins have been reported with slightly twisted chromophores. We have previously shown that the protein cavity surrounding the chromophore in wild-type GFP is not complementary with a planar chromophore. This study shows that the crystal structure of wild-type GFP is not an anomaly: most of the GFP and GFP-like proteins in the protein databank have a protein matrix that is not complementary with a planar chromophore. When the pi-conjugation across the ethylenic bridge of the chromophore is removed the protein matrix will significantly twist the freely rotating chromophore from the relatively planar structures found in the crystal structures. The possible consequences of this nonplanar deformation on the photophysics of GFP are discussed. A volume analysis of the cis-trans-isomerization of HBDI, a GFP chromophore model compound, reveals that its hula-twist motion is volume conserving. This means that, if the GFP chromophore or GFP chromophore model compounds undergo a cis-trans-isomerization in a volume-constricting medium, such as a protein matrix or viscous liquid, it will probably isomerize by means of a HT-type motion.     

Trans-cis isomerization is responsible for the red-shifted fluorescence in variants of the red fluorescent protein eqFP611

An important class of red fluorescent proteins (RFPs) feature a 2-iminomethyl-5-(4-hydroxybenzylidene)imidazolinone chromophore. Among these proteins, eqFP611 has the chromophore in a coplanar trans orientation, whereas the cis isomer is preferred by other RFPs such as DsRed and its variants. In the photoactivatable protein asFP595, the chromophore can even be switched from the nonfluorescent trans to the fluorescent cis state by light. By using X-ray crystallography, we have determined the structure of dimeric eqFP611 at high resolution (up to 1.1 A). In the far-red emitting eqFP611 variant d2RFP630, which carries an additional Asn143Ser mutation, the chromophore resides predominantly (approximately 80%) in the cis isomeric state, and in RFP639, which has Asn143Ser and Ser158Cys mutations, the chromophore is found completely in the cis form. The pronounced red shift of excitation and emission maxima of RFP639 can thus unambiguously be assigned to trans-cis isomerization of the chromophore. Among RFPs, eqFP611 is thus unique because its chromophore is highly fluorescent in both the cis and trans isomeric forms.     

Kinetics of acid-induced spectral changes in the GFPmut2 chromophore

We have used a nanosecond pH-jump technique, coupled with simultaneous transient absorption and fluorescence emission detection, to characterize the dynamics of the acid-induced spectral changes in the GFPmut2 chromophore. Disappearance of the absorbance at 488 nm and the green fluorescence emission occurs with a thermally activated, double exponential relaxation. To understand the source of the two transients we have introduced mutations in amino acid residues that interact with the chromophore (H148G, T203V, and E222Q). Results indicate that the faster transient is associated with proton binding from the solution, while the second process, smaller in amplitude, is attributed to structural rearrangement of the amino acids surrounding the chromophore. The protonation rate shows a 3-fold increase for the H148G mutant, demonstrating that His148 plays a key role in protecting the chromophore from the solvent. The deprotonation rate for T203V is an order of magnitude smaller, showing that the hydrogen bond with the hydroxyl of Thr203 is important in stabilizing the deprotonated form of the chromophore. A kinetic model suggests that, in addition to protecting the chromophore from the solvent, His148 may act as the primary acceptor for the protons on the way to the chromophore.     

Environmental and excitonic effects on the first hyperpolarizability of polar molecules and related dimers

We investigate the second-order nonlinear optical properties of a push-pull chromophore in different external and supramolecular environments, through a combined experimental and theoretical approach. In particular, we compare the first hyperpolarizability (beta) of a model dipolar and polarizable chromophore with that of a charged analogue and of a molecular dimer based on the chromophore itself. We find that the beta value of the model chromophore in solutions of low-polarity solvents is strongly affected by association effects, already at concentrations of 10 (-3) M. The presence of a positive charge in close proximity to the chromophore is found to lead to a 100% increase of the beta response of the model push-pull chromophore. This effect is of major importance for biological applications, in particular when chromophores are used as markers in charged anisotropic environments. Finally, excitonic effects, beyond the Frenkel exciton approximation, are discussed for the dimer and found to be more important the higher the order of nonlinearity is.