第二代抗癌药物卡铂与L-硒代蛋氨酸和L-蛋氨酸的相互作用研究

硒作为一种生命体所必须的微量营养元素，近年来由于其在防癌犤１，２犦和抗氧化，增强免疫力等方面的作用而越来越受到广泛的关注。其中L－硒代蛋氨酸（L－Se－MetH）作为一种有效的防癌剂正处在临床试验阶段犤２犦。对于硒代蛋氨酸在抑制癌细胞生长和在体内的抗氧化作用的机理已有很多报导犤３～５犦，但作为生物体的主要含硒氨基酸之一，与L－蛋氨酸（L－MetH）相比，它与金属离子的作用却少见报导犤６，７犦。本文利用电喷雾质谱（ESMS）和２D犤１H－１５N犦HSQCNMR的手段研究了第二代铂类抗癌药物卡铂（犤Pt（NH３）２（CB…     

Inhibition of microbial xylitol production by acetic acid and its relation with fermentative parameters

Precipitated sugarcane bagasse hemicellulosic hydrolysate containing acetic acid was fermented by Candida guilliermondii FTI 20037 under different operational conditions (pH 4.0 and 7.0, three aeration rates). At pH 7.0 and k _L a of 10 (0.75 vvm) and 22.5/h (3.0 vvm) the acetic acid had not been consumed until the end of the fermentations, whereas at the same pH and k _L a of 35/h (4.5 vvm) the acid was rapidly consumed and acetic acid inhibition was not important. On the other hand, fermentations at an initial pH of 4.0 and k _L a of 22.5 and 35/h required less time for the acid uptake than fermentations at k _L a of 10/h. The acetic acid assimilation by the yeast indicates the ability of this strain to ferment in partially detoxified medium, making possible the utilization of the sugarcane bagasse hydrolysate in this bioprocess. The effects on xylitol yield and production are reported.     

新型L-苯丙氨酸桥联双卟啉的合成与光谱表征

用L-苯丙氨酸和5-[对-(4-溴丁氧基、己氧基、辛氧基)苯基]-10,15,20-三苯基卟啉合成3种新型L-苯丙氨酸桥联双卟啉,并通过质谱、¹H核磁共振谱、元素分析、红外光谱、紫外光谱对其结构进行了表征。测试并研究了它们在4 000~400 cm^-1范围内的傅里叶变换红外光谱,对主要谱带进行了经验归属。     

Study on the interaction between an ionic liquid and L-tryptophan by fluorescence spectroscopic technique

In this work, the interaction of an ionic liquid (IL) 1-octyl-3-methylimidazolium chloride ([Omim]Cl) and L-tryptophan was investigated with fluorescence spectroscopic method. The quenching mechanism and binding characteristics of [Omim]Cl with L-tryptophan at different temperatures were studied from fluorescence measurement. The thermodynamic parameters such as free energy change (ΔG), enthalpy change (ΔH) and entropy change (ΔS), were calculated by thermodynamic equations. The experimental results indicated that [Omim]Cl and L-tryptophan had weak interaction and the mechanism of quenching belonged to static quenching. Hydrogen bonds and van der Waals interactions played important roles in the binding of [Omim]Cl with L-tryptophan.     

Complex formation of curium(III) with amino acids of different functionalities: L-threonine and O -phospho-L-threonine

The speciation of curium(III) with L-threonine and O-phospho-L-threonine was determined by time-resolved laser-induced fluorescence spectroscopy (TRLFS) at trace Cm(III) concentrations (3?×?10^?7?M). Curium species of the type M_pH_qL_r were identified in the L-threonine- and O-phospho-L-threonine system. These complexes are characterized by their individual luminescence spectra and luminescence lifetimes. The following formation constants were determined (a) for L-threonine: log?β₁₀₁?=?6.72?±?0.07, log?β₁₀₂?=?10.22?±?0.09, and log?β_1–22?=?(7.22?±?0.19) at ionic strength I?=?0.5?M and (b) for O-phospho-L-threonine: log?β₁₂₁?=?18.03?±?0.13 and log?β₁₁₁?=?14.17?±?0.09 at ionic strength I?=?0.154?M. Possible structures of the identified curium species are discussed on the basis of the luminescence lifetime measurements and the magnitude of the formation constants.     

Synthesis and in vitro Property Study of Polyaspartamides

Cationic polyaspartamides including poly-α,β-[N＇-（2-aminoethyl）-L-aspartamide] （PAEA）, poly-α,β-[N＇-（4- aminobutyl）-L-aspartamide] （PABA）, poly-α,β-[N＇-（6-aminohexyl）-L-aspartamide] （PAHA）, poly-α,β-[N＇-（5-amino- 3-azapentyl）-L-aspartamide] （PAAPA） and poly-α,β-[N＇-（8-amino-3,6-diazaoctyl）-L-aspartamide] （PADAOA） were synthesized from polysuccinimide. Their properties were evaluated by ^1H NMR, IR, GPC, fluorescence measurement and in vitro cytotoxicity assays. The molecular weights per primary amine charge group of PAEA（1） （Mn= 2229）, PAAPA and PADAOA are 212, 279, and 226. Polyaspartamides including PAEA（1）, PAAPA, PADAOA and low molecular weight PAHA are markedly less toxic than poly（ethyleneimine） and poly（L-lysine）, however, PABA and higher molecular weight PAHA are slightly less toxic than poly（L-lysine）. Cell cytotoxicity of PAHA was seen to decrease with increasing molecular weight of PAHA, due to water solubility reduction. The negatively charged plasmid DNA has been found to be completely neutralized and complexed by the cationic polyaspartamides at an N/P ratio of 5 ： 1 to 10 ： 1, forming self-assembled polyplexes via ionic interactions. These polyaspartamide/DNA complexes possess stable zeta potentials and mean particle diameters of about 180 nm for PAEA （1）/DNA and PAAPA/DNA complexes and 280 nm for PADAOA/DNA complexes.     

Influence of a new axial impeller on K L a and xylanase production by Penicillium canescens 10-10c

The effects of a new axial impeller (HTPG4) on oxygen volumetric transfer coefficient, K _L a, and xylanase production by Penicillium canescens 10-10c were studied and compared for dual-impeller systems, one with one DT4 impeller below and one HTPG4 above (DT4-HTPG4) and one with two DT4 (DT4-DT4) impellers, in a 5-L bioreactor. The volumetric coefficient of oxygen transfer was measured in culture medium using a gassing-out method at different gassing rates and agitation speeds. We observed that the DT4-HTPG4 combination provided better K _L a performance than the DT4-DT4 combination. The two combinations were also tested for their influence on xylanase production by a filamentous microorganism; P. canescens 10-10c. These experiments demonstrated that the DT4-HTPG4 combination impeller enhanced enzyme production up to 23% compared with the DT4-DT4 combination at an aeration rate of 1 vvm and an agitation speed of 600 rpm. The main cause for this difference is thought to be a higher shear stress generated by the DT4-DT4 combination, which damages the mycelium of P. canescens and decreases xylanase production.     

Fluorescent sensing layer for the determination of<Emphasis Type="SmallCaps"> L</Emphasis>-malic acid in wine

An enzymatic method for determining L-malic acid in wine based on an L-malate sensing layer with nicotinamide adenine dinucleotide (NAD⁺), L-malate dehydrogenase (L-MDH) and diaphorase (DI), immobilized by sol-gel technology, was constructed and evaluated. The sol-gel glass was prepared with tetramethoxysilane (TMOS), water and HCl. L-MDH catalyzes the reaction between L-malate and NAD⁺, producing NADH, whose fluorescence (λ _exc = 340 nm, λ _em = 430 nm) could be directly related to the amount of L-malate. NADH is converted to NAD⁺ by applying hexacyanoferrate(III) as oxidant in the presence of DI. Some parameters affecting sol-gel encapsulation and the pH of the enzymatic reaction were studied. The sensing layer has a dynamic range of 0.1–1.0 g/L of L-malate and a long-term storage stability of 25 days. It exhibits acceptable reproducibility [s _r(%)≈10] and allows six regenerations. The content of L-malic acid was determined for different types of wine, and polyvinylpolypyrrolidone (PVPP) was used as a bleaching agent with red wine. The results obtained for the wine samples using the sensing layer are comparable to those obtained from a reference method based on UV-vis molecular absorption spectrometry, if the matrix effect is corrected for.     

Complex Formation of Cyclodextrins with Various Thiophenes and their Polymerization in Water: Preparation of Poly-pseudo-rotaxanes containing Poly(thiophene)s

Cyclodextrins (α-CD, β-CD and 2,6-di-O-dimethyl-β-CD (DM-β-CD)) were found to form inclusion compounds with thiophenes (thiophene (T), bithiophene (2T)) in water and in crystalline states. The structures of α-CD–T, β-CD–2T, and DM-β-CD–2T inclusion complexes were determined by X-ray crystallography. DM-β-CD forms a 1:1 cage type complex with 2T. In contrast, β-CD formed 2:3 (CD:guest) complexes with thiophene and α-CD formed 2:3 complexes, both of the channel type. These inclusion complexes were found to polymerize by FeCl₃ in the inclusion compounds in water. The products were formed poly-pseudo-rotaxane between cyclodextrins and poly(thiophene) characterized by IR, ¹H-NMR and ¹³C CP/MAS NMR. The molecular weights of the poly-pseudo-rotaxanes with poly(thiophene) were determined by the MALDI-TOF mass spectra to be 3000–5000. In comparison between poly-pseudo-rotaxane (DM-β-CD–poly(thiophene)), authentic poly(thiophene) and the washed DM-β-CD–poly(thiophene) which was washed with DMF to dethread DM-β-CD, these poly-pseudo-rotaxane was characterized by Raman, UV–vis and fluorescence spectra. The maximum emission band of DM-β-CD–poly(thiophene) shifted to a shorter wavelength. The hypsochromic shift was derived from poly-pseudo-rotaxane with DM-β-CD.     

Unperturbed dimension of poly-N-vinylcarbazole

Osmotic-pressure, viscosity, and light-scattering measurements have been carried out on dilute solutions of poly-N-vinylcarbazole fractions (4 < 10^-4M < 230) in toluene, dioxane, and benzene. The theta temperature for poly-N-vinylcarbazole in toluene solutions has been found to be 37 ± 1°C. The intrinsic viscosity of poly-N-vinylcarbazole in toluene at 37°C is represented by [η]θ = 76.2 × 10^?3M?_n^0.50. Values of the characteristic ratios (〈L²〉₀/M)^1/2 and σ = (〈L²〉₀/〈L²〉_0f)^1/2 have been obtained as 633 × 10^?11 and 2.85, respectively. It appears that the large σ value is due to the steric repulsion between large side groups.     

Unperturbed dimensions of polystyrene derivatives. II. Poly-3,4-dichlorostyrene and poly-p-cyclohexylstyrene

The relationship of intrinsic viscosity to the number-average molecular weight has been obtained for poly-3,4-dichlorostyrene and poly-p-cyclohexylstyrene in a few solvents. Values of (〈L²〉₀/M)^1/2 have been estimated for poly-3,4-dichlorostyrene and poly-p-cyclohexylstyrene through the use of the treatment of Stockmayer and Fixman. The values of (〈L〉₀/M)^1/2 have been obtained as 2.18 ± 0.08 and 2.52 ± 0.07 for poly-3,4-dichlorostyrene and poly-p-cyclohexylstyrene, respectively. The σ value of a series of polystyrene derivatives has been found to increase with the bulk of side groups. This seems to indicate that the σ value is mainly determined by the steric repulsion between side groups.     

Knudsen effusion mass spectrometric determination of mixing thermodynamic data of liquid Ag–In–Sn alloy

The vaporisation of a liquid Ag–In–Sn system has been investigated at 1273–1473 K by Knudsen effusion mass spectrometry (KEMS) and the data fitted to a Redlich–Kister–Muggianu (RKM) sub-regular solution model. Nineteen different compositions have been examined at six fixed indium mole fractions, X_In = 0.10, 0.117, 0.20, 0.30, 0.40 and 0.50. The ternary L-parameters, the thermodynamic activities and the thermodynamic properties of mixing have been evaluated using standard KEMS procedures and from the measured ion intensity ratios of Ag⁺ to In⁺ and Ag⁺ to Sn⁺, using a mathematical regression technique described by us for the first time. The intermediate data obtained directly from the regression technique are the RKM ternary L-parameters. From the obtained ternary L-parameters the integral molar excess Gibbs free energy, the excess chemical potentials, the activity coefficients and the activities have been evaluated. Using the temperature dependence of the activities, the integral and partial molar excess enthalpies and entropies were determined. In addition, for comparison, for some compositions, also the Knudsen effusion isothermal evaporation method (IEM) and the Gibbs–Duhem ion intensity ratio method (GD-IIR) were used to determine activities and good agreement was obtained with the data obtained from fitting to the RKM model.     

Microwave-assisted synthesis,crystal structure and toxicity of <Emphasis Type="Italic">L</Emphasis>-aspartic acid zinc spiral linear supramolecular polymer

L-aspartic acid zinc was synthesized by a rapid and convenient method in high yield under microwave conditions, and its single crystal structure was analyzed by X-ray diffraction. The structure unit of the title compound is [Zn(L-Asp)(H₂O)₂]·H₂O, which is a bicyclo-complex forming a spiral linear polymer via coordination bonds. The spiral linear polymers are assembled as a three-dimensional supramolecule by intermolecular hydrogen bonds. The crystal belongs to the orthorhombic crystal system, P2(1)2(1)2(1) space group, a=0.7830(3) nm, b=0.9369(4) nm, c=11.599(5) nm, α=β=γ=90.00°, V=0.8509(6) nm³, Z=4, Dc=1.955 g/cm³, F(000)=512, μ=2.289. The toxicity of the title compound is lower than that of glutamic acid zinc and zinc sulfate.     

Formation of poly-p-phenylene thin films and their composites with fullerene by discrete evaporation in vacuum

The effect of parameters of discrete evaporation of poly-p-phenylene (PPP) and C₆₀ on quality of the films formed was studied, PPP and PPP/C₆₀ composite films and heterostructures based on these materials were prepared. It was established that the conjugation length of PPP macromolecules consists of –9–10 units, and they can be electrochemically transformed into the radical cation state at a potential of 2.10 V. Glassy carbon-PPP-C₆₀-Al heterostructures with a rectification ratio of 10⁶–10⁸ were formed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No, 12, pp, 2918–2921, December, 1996.     

Aggregate, Polymer and Cluster Formation from Metal-Imino Carboxylate Complexes

Reaction of tris-(2-aminoethyl)amine (tren) andthe sodium salt of an -ketocarboxylic acid, typically sodium pyruvate, affordsin the presence of a lanthanide ion aseries of complexes and aggregates includingmononuclear, cyclic tetranuclear and polymerspecies of [L¹]^3- ([L¹]^3-=N[CH₂CH₂N=C(CH₃)COO^-]³).The aggregation of these and related d-block elementcomplexes with Na⁺ ions leadsto the formation of polymeric materials, and thefactors influencing the formation and controlof these various aggregation states are discussed.Metal cations also template the aggregationof the fragment [Ni(L²)] ([L²]^2- =CH₂[CH₂N = C(CH₃)COO^-]₂)to give, in high yield, the polynuclearaggregates {[Ni(L²)]₆M}^x+(M = Nd, Pr, Ce, La, x = 3; M = Sr, Ba, x = 2). The structures of{[Ni(L²)]₆M}^x+ show aninterstitial twelve co-ordinate, icosahedralcation M^x+ encapsulated by six [Ni(L²)]fragments. In the presence ofNa⁺, aggregation of [Ni(L²)] fragments affords {[Ni(L²)]₉Na₄(H₂O)(MeOH)(ClO₄)}³⁺ thestructure of whichshows four Na⁺ ions templating the formation ofa distorted tricapped trigonal prismatic[Ni(L²)]₉ cage. Thus, control overconstruction of various polynuclear cages viaself-assembly at octahedral junctions can beachieved using main group, transition metaland lanthanide ion templates.     

Different crystallinity of poly(d,l-lactide-co-p-dioxanone) copolymers acquired by control of chain microstructure

Poly(d,l-lactide-co-p-dioxanone)(P(LA-co-PDO)) copolymers with different chain microstructures were synthesized by one-step or two-step bulk ring-opening polymerizations of d,l-lactide(LA) and p-dioxanone(PDO) monomers using stannous octoate [Sn(Oct)_2]/n-dodecanol as the initiating system.The average sequence lengths of the lactidyl(L_(LA)) and dioxanyl(L_(PDO)) units were calculated from the ~1H NMR spectra.It was found that both L_(LA) and L_(PDO) values from the two-step syntheses were significantly ...     

Thermal and mechanical characterization of plasticized poly (L-lactide-co-D,L-lactide) films for food packaging

In this work amorphous poly(L-lactide-co-D,L-lactide) (PLLA/PDLLA) was blended with four different commercial adipates to obtain films with enhanced mechanical and thermal properties. Efficiency of plasticizers was evaluated by studying their compatibility with the polymer and their effect on its glass transition temperature. All plasticizers were compatible with the matrix up to a critical composition depending on its molar mass. The addition of plasticizers caused a decrease in elastic modulus and tensile stress, meanwhile elongation at break had a maximum increase for polyadipates with the lower molar mass. Monomeric adipate showed some migration at concentration higher than 10 mass%, while the addition of the higher molar mass plasticizer lead to eventual phase separation. Polyadipates with low molar mass showed a promising behaviour to overcome the brittleness in PLLA/PDLLA films.     

Spectroscopic,Magnetic and Thermal Investigations on Cu(II), Mn(II), Co(II) and Fe(III) Complexes with Glutamyl Nitroanilide

New complexes CuL₂×2H₂O, CoL₂×3H₂O, MnL₂×2H₂O and FeL₃×2H₂O, L=γ-L -glutamyl-5-(p-nitroanilide), were synthesized and characterized by their spectral, magnetic and thermal properties. The thermal stabilities of the synthesized complexes were examined in the temperature range 20–500°C. In all these complexes γ-L -glutamyl-5-(p -nitroanilide) acts as a bidentate ligand, its coordination involving the carbonyl oxygen and the nitrogen atom of the second amino group. The local structure around the Cu(II) ion is pseudotetrahedral. In the Co(II), Mn(II) and Fe(III) complexes, the metal ions are in the high-spin form, with octahedral stereochemistry. This revised version was published online in August 2006 with corrections to the Cover Date.     

Complexes of dioxouranium(VI) with zwitter-ionic forms of Bi- and tetra-dentateSchiff bases

Potentially bi- and tetra-dentateSchiff bases derived from salicylaldehyde react with hydrated uranyl salts to give complexes: UO₂H₂ LX ₂, UO₂H₂ LX ₂ and UO₂(HL)₂ X ₂ [H₂ L=N,N-propane-1,3-diylbis(salicylideneimine), H₂ L=N,N-ethylenebis(salicylideneimine) and HL=N-phenylsalicylideneimine;X ^–=Cl^–, Br^–, I^–, NO₃ ^–, ClO₄ ^–, and NCS^–]. Because of marked spectral similrities with the structurally known Ca(H₂ L) (NO₃)₂, theSchiff bases are coordinated through the negatively charged phenolic oxygen atoms and not the nitrogen atoms of the azomethine groups which carry the protons transferred from phenolic groups on coordination. Halide, nitrate, perchlorate and thiocyanate groups are covalently bonded to the uranyl ion, resulting a 6-coordinated uranium ion in the halo and thiocyanato complexes and 8-coordinated in nitrato and perchlorato complexes.

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Komplexe von Dioxouranyl(VI) mit zwitterionischen Formen von zwei- und vierzähnigen Schiff-Basen

Zusammenfassung Von Salizylaldehyd abgeleitete zwei- und vierzähnigeSchiff-Basen reagieren mit hydratisierten Uranylsalzen zu Komplexen folgenden Typs: UO₂H₂ LX ₂, UO₂H₂ LX ₂ und UO₂(HL)₂ X ₂ [H₂ L=N,N-Propan-1,3-diylbis(salicylidenimin), H₂ L=N,N-Ethylen-bis(salicylidenimin) und HL=N-Phenylsalicylidenimin;X ^–=Cl^–, Br^–, I^–, NO₃ ^–, ClO₄ ^– und NCS^–]. Auf Grund eindeutiger spektraler Ähnlichkeiten mit dem bekannten Ca(H₂ L) (NO₃)₂ wird auf Koordination über die negativ geladenen phenolischen Sauerstoffatome (und nicht über die Azomethin-Stickstoffe) geschlossen. Die AnionenX ^– sind kovalent an das Uranyl-Ion gebunden; damit ergibt sich ein hexakoordiniertes Uranyl-Ion für die Halogen- und Thiocyanat-Komplexe und Oktakoordination für die Nitrat- und Perchlorat-Komplexe.

     

Polymer supported 5,10,15,20-tetrakis(phenoxy acetic acid)porphyrin derivative for separation and preconcentration of d- and f-electron metals

5,10,15,20-tetrakis(phenoxy acetic acid) porphyrin (PAAP) was covalently linked to Merrifield chloromethylated resin. Characterization of PAAP and the modified polymeric matrix were performed by ¹H NMR, FTIR and elemental analysis. The sorbent was used for the separation and enrichment of the d-electron metals (Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)) at pH 6–8 and of the f-electron metals U(VI) and Th(IV) at pH 4–5. The metals ions were preconcentrated with a concentration factor range of 115–215 and then determined by flame atomic absorption spectrometry or visible spectrophotometry using Arsenazo(III). The retained metals were eluted with 2.0 mol L⁻¹ HNO₃ in the case of the d-electron metals and 0.1/0.25 mol L⁻¹ HCl in the case of the f-electron metals. The procedure was validated by analyzing the NIST standard reference material 2709 (San Joaquin Soil). Correspondence: Melek Merdivan, Chemistry Department, Faculty of Arts and Sciences, Dokuz Eylul University, 35160 Buca, Izmir, Turkey