Photochemically induced fluorescence investigation of aβ-cyclodextrin: Azure A inclusion complex and determination of analytical parameters

The photooxidation of Azure A and fluorescence properties of Azure A and its photoproduct have been investigated in aqueous media and in the presence of-cyclodextrin (-CD). The fluorescence intensity of the complex formed between the photoproduct and -CD was found to be three times higher than that of the uncomplexed Azure A photoproduct. A complex formation constant of 110±40 M^–1 was calculated using the Benesi-Hildebrand treatment of the fluorescence emission data. Although the stoichiometry of the Azure A photoproduct: -CD complex was found to be 1: 1, it seems that the Azure A structure is only partially included. Calibration graphs were plotted for the free Azure A photoproduct and the photogenerated product included in -CD. The analytical parameters and quantification limits were determined.     

Effects of tetraalkylaluminoxane activators on ethylene polymerization catalyzed by iron-based complexes

Five different tetraalkylaluminoxanes, tetraisobutylaluminoxane (A1), ethyltriisobutylaluminoxane (A2), diethyldiisobutylaluminoxane (A3), triethylisobutylaluminoxane (A4) and tetraethylaluminoxane (A5), were prepared to polymerize ethylene in the presence of iron complexes [((2,6-RPh)NC(Me))₂C₅H₃N]FeCl₂ (RMe, M1; Riso-Pr, M2). Except M1/A1 and M2/A1, all other catalyst systems produced polyethylene with pronounced broad or bimodal molecular weight distribution (MWD). It was demonstrated that the low-MW fractions of these broad- or bimodal-MWD polyethylenes result from the chain transfer reaction to the alkylaluminium containing the Al-Et groups in the activator. As the Al/Fe ratio and the amount of the Al-Et groups in the activators increased in the order: A1 < A2 < A3 < A4 < A5, the polymerization activity and the low-MW fraction of broad- or bimodal-MWD polyethylene increased and the high-MW fraction correspondingly reduced.     

High-performance anion-exchange chromatographic study of desialylated human alpha 1-acid glycoprotein variants. Development of a fractionation method for the protein slow variants

The three main desialylated variants (F1, S and A) of human alpha 1-acid glycoprotein (AAG), a serum acute-phase reactant, were analysed by high-performance anion-exchange chromatography in order to determine their optimum separation conditions. The analysis consisted of three steps, as follows: (1) A desialylated commercial AAG was separated into one "fast"- and one "slow"-migrating fraction by preparative isoelectrofocusing. The "fast" and "slow" fractions were shown to contain the F1 variant and a mixture of the S and A variants, respectively. (2) The pH titration curves of these two fractions were then measured by strong anion-exchange chromatography with several buffer systems of increasing pH. From the data obtained, it was not possible to select the optimum conditions to separate the "fast" variant F1 from the "slow" variants A and S. However, the S and A variants were shown to ionize very differently. (3) The specific fractionation of the S and A variants was therefore carried out by anion-exchange chromatography under operating conditions based on the data obtained from the study of their pH titration curves. This was performed both with the "slow"-migrating fraction obtained by preparative isoelectrofocusing of commercial AAG and with an AAG (containing only variants S and A) purified from an individual serum on immobilized Cibacron Blue F3G-A. Identification of the fractionated proteins was achieved by analytical isoelectrofocusing.     

A theoretical study on the alkene insertion step in Rh-Yanphos catalyzed hydroformylation

This paper studied the mechanism of the alkene insertion elementary step in the asymmetric hydroformylation （AHF） catalyzed by RhH（CO）2[（R,S）-Yanphos] using four alkene substrates （CH2=CH- Ph, CH2=CH-Ph-（p）-Me, CH2=CH-C（==O）OCH3 and CH2=CH-OC（=O）-Ph, abbreviated as A1-A4）. Interestingly, the equatorial vertical coordination mode （A mode） with respect to the Rh center was found for AI and A2 but not for A3 and A4, although the equatorial in-plane coordination mode （E mode） was found for A1 -A4. The relative energy of the E mode of the -q2-intermediates is lower than that of the A mode. In the alkene insertion step, Path 1 is more favorable than Path 2 for this system. As for AI and A2, there could be a transformation between 2eq and 2ax.     

Resonance in random π-network polymers

The electronic structure of a -network polymer with random numbers of two types of monomer units is considered in a conjugated circuit resonance-theoretic framework. A transfer-matrix technique for computing relevant ensemble-average energies is described and applied to a few example simple benzenoid systems. A type of long-range ordering is noted to be relevant, and some of its implications are discussed.Research supported by the Robert A. Welch Foundation of Houston, Texas, USA.     

Comparative efficacy of locally isolated fungal strains for Pb(II) removal and recovery from water

The present investigation aimed to study and compare the efficiency of non-viable fungal isolates to remove divalent lead (Pb(II)) from aqueous streams. The selected fungal isolates showed identity with Aspergillus caespitosus, Aureobasidium sp. RBSS-303 and Aspergillus flavus HF5 as confirmed using gene sequencing of ITS regions of the ribosomal DNA (rDNA). The obtained equilibrium data for Pb(II) biosorption of A. caespitosus fitted better to Langmuir isotherm with maximum sorption capacity of 351.0 mg/g and A. sp. RBSS-303 and A. flavus HF5 showed good fit to Freundlich isotherm with maximum sorption capacity of 271.5 and 346.3 mg/g respectively. The values of thermodynamic factors ascertained the nature of adsorption process is endothermic with A. caespitosus and A. flavus HF5 but exothermic with A. sp. RBSS-303. The experimental data for Pb(II) biosorption fits very well to pseudo second order kinetic model. With HCl the maximum 85.5, 75.3, 73.7% recovery of Pb(II) was obtained from A. caespitosus, A. sp. RBSS-303 and A. flavus HF5, respectively. The observed percentage loss in sorption capacity of Pb(II) was 3.9% by A. flavus HF5, 12.2% by A. caespitosus and 26.6% by A. sp. RBSS-303 after five cyclic studies of sorption and desorption. Results from the study confirmed the efficiency order of A. caespitosus > A. flavus HF5 > A. sp. RBSS-303 to remove and recover Pb(II) from aqueous solution. Finally, the fungal biosorbents can be used as soil conditioning agent after compositing into valuables fungal protein.     

Novel carotenoid pyropheophorbide A esters from abalone

A series of carotenoid pyropheophorbide A esters, fucoxanthin pyropheophorbide A ester (1), halocynthiaxanthin 3′-acetate pyropheophorbide A ester (2), lutein pyropheophorbide A esters (3) and (4), and mutatoxanthin pyropheophorbide A ester (5), were isolated from the viscera of the abalone Haliotis diversicolor aquatilis. These structures were determined based on UV-vis, MS, and NMR spectroscopic data.     

Synthesis of P-Chiral [ 18 O]-Labeled Isotopomeric Oligo(deoxyribonucleoside Phosphorothioate)s and Phosphates

Diastereomerically pure, isotopically labeled 5'- O -DMT-nucleoside-3'- O -(2-thio-4,4-"spiro"-pentamethylene-1,3,2-[ 18 O]oxathiaphospholane)s and -(2-oxo-4,4-"spiro"-pentamethylene-1,3,2-[ 18 O]oxathiaphospholane)s suitable for stereocontrolled synthesis of P-chiral oligonucleotide [ 18 O]phosphorothioates and [ 18 O]phosphates were synthesized. Obtained in that way "chimeric" oligonucleotide d[A PO A PS-Rp,Sp A PS-Rp , Sp A PS-Rp C PS(18O)-Rp G PS-Rp T PS-Rp T PS-Rp,Sp T PO T] was used for determination of the stereochemistry of hydrolysis by endonuclease from Serratia marcescens .     

Acquiring Structural Information on Virus Particles with Charge Detection Mass Spectrometry

Charge detection mass spectrometry (CDMS) is a single-molecule technique particularly well-suited to measuring the mass and charge distributions of heterogeneous, MDa-sized ions. In this work, CDMS has been used to analyze the assembly products of two coat protein variants of bacteriophage P22. The assembly products show broad mass distributions extending from 5 to 15 MDa for A285Y and 5 to 25 MDa for A285T coat protein variants. Because the charge of large ions generated by electrospray ionization depends on their size, the charge can be used to distinguish hollow shells from more compact structures. A285T was found to form T = 4 and T = 7 procapsids, and A285Y makes a small number of T = 3 and T = 4 procapsids. Owing to the decreased stability of the A285Y and A285T particles, chemical cross-linking was required to stabilize them for electrospray CDMS.

Graphical Abstract

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Attenuation of Tumor Development in Mammary Carcinoma Rats by Theacrine,an Antagonist of Adenosine 2A Receptor

Caffeine has been reported to induce anti-tumor immunity for attenuating breast cancer by blocking the adenosine 2A receptor. Molecular modeling showed that theacrine, a purine alkaloid structurally similar to caffeine, might be an antagonist of the adenosine 2A receptor equivalent to or more effective than caffeine. Theacrine was further demonstrated to be an effective antagonist of the adenosine 2A receptor as its concurrent supplementation significantly reduced the elevation of AMPK phosphorylation level in MCF-7 human breast cells induced by {"type":"entrez-protein","attrs":{"text":"CGS21680","term_id":"878113053","term_text":"CGS21680"}}CGS21680, an agonist of adenosine 2A receptors. In an animal model, the development of mammary carcinoma induced by 7,12-Dimethylbenz[a]anthracene in Sprague–Dawley rats could be attenuated by daily supplement of theacrine of 50 or 100 mg/kg body weight. Both expression levels of cleaved-caspase-3/pro-caspase-3 and granzyme B in tumor tissues were significantly elevated when theacrine was supplemented, indicating the induction of programmed cell death in tumor cells might be involved in the attenuation of mammary carcinoma. Similar to the caffeine, significant elevation of interferon-γ and tumor necrosis factor-α was observed in the serum and tumor tissues of rats after the theacrine supplement of 50 mg/kg body weight. Taken together, theacrine is an effective antagonist of adenosine 2A receptors and possesses great potential to be used to attenuate breast cancer.     

Thermal denaturation of ribonuclease T1 a DSC study

The thermal denaturation of microbial Ribonuclease T1 (RNAase T1) as a function ofpH, was studied by means of DSC microcalorimetry. The midpoint denaturation temperatures, enthalpy changes and heat capacity changes of Ribonuclease T1 were compared with those obtained for pancreatic Ribonuclease A (RNAase A). It was found that the microbial T1 protein undergoes a more complex conformational transition than the simple two-state transition shown by Ribonuclease A. The hypothesis of the presence of a molten globule form is discussed. The conformational stability of RNAase T1 is lower than that of RNAase A at highpH values. Indeed, the maximum stability of RNAase T1 occurs atpH 5, whereas that of RNAase A occurs atpH 8. AtpH=3.7 an irreversible aggregation phenomenon was indicated by the existence of a reproducible exothermic peak. The conformational transition of RNAase T1 is reversible in the range ofpH 4.5–7.0, whereas it becomes irreversible atpH8.0 as for RNAase A.This work was financed by the National Research Council (C.N.R.-Rome) and by Ministry of University and Scientific and Technological Research.     

Newly developed chemical probes and nano-devices for cellular analysis.

A cellular analyzing system including a "real-time cellular imaging system" and a "comprehensive analyzing system for cellular responses" was developed. A "real-time cellular imaging system" is a system used to measure real-time imaging of multiple phenomena of a single cell with high special and temporal resolutions for the purpose to understand the pathology and physiology in a single cell and realize to single cell level diagnosis. A "real-time cellular imaging system" includes multi-probe imaging with AFM (atomic force microscopy), optical and SECM (scanning electrochemical microscopy) modes, which provides us with topological information and biochemical reactions at the local area of the interior and exterior of a cell. Scanning electrochemical/optical microscopy was applied to image PC12 cells. On the other hand, cells respond to their specific substances via their ligands. Therefore, the comprehensive analysis of protein-protein interaction is the important issue to determine the functions of cells. For this purpose, a "comprehensive analysis system for cellular responses" was developed. This system is based on SPR (surface plasmon resonance) and MS (mass spectrometry) using a nano-fabricated substrate. The interaction between IL-1 beta and anti-IL-1 beta antibodies was detected.     

The synthesis of ω-thienylalkane acids from ω-chloroalkane acids

Summary We have worked out a preparative method for the synthesis of -thienylalkane acids by acylation of thiophene with -chloroalkane acid chlorides followed by conversion of the resulting -chloroalkyl(2-thienyl)ketones into the corresponding acids by reaction with sodium malonic ester or potassium cyanide, and reduction of the resulting products with their simultaneous hydrolysis.Here and later we mean -(2-thienyl)alkne acids.We take this opportunity to thank R. Kh. Freidlina, A. A. Beér, and M. A. Besprozvannii for giving us enough -chloroalkane acids.     

Effects of 2-Hydroxypropyl-b-cyclodextrin on Polymorphic Transition of Chlorpropamide in Various Conditions: Temperature, Humidity and Moulding Pressure

The amorphous complex of 2-hydroxypropyl--cyclodextrin (HP--CyD) with an oral hypoglycemic agent, chlorpropamide (CPM), in a molar ratio of 1:1 was prepared by the spray-drying method. The effects of storage (temperature and humidity) and moulding pressure on the polymorphic transition of CPM in HP--CyD matrix were investigated, in comparison with those of the CPM polymorphs, Form A (stable form) and Form C (metastable form). The formation of an amorphous complex of CPM with HP--CyD was confirmed by powder X-ray diffractometry and differential scanning calorimetry. During storage at various temperature and humidity conditions, the metastable Form C of CPM converted to the stable Form A, where the conversion proceeded according to the Jander equation with an activation energy of 51 kJ/mol (25–60–°C) and a reaction-order of 1.55 with respect to water content (relative humidity (RH) 20–75%). No polymorphic transition of Form A crystals was observed under the experimental conditions. In the case of the amorphous HP--CyD complex, Form C crystals were slowly produced, but the further conversion of the resulting Form C to Form A was markedly suppressed in HP--CyD matrix. Upon compression (2000kg/cm²), Forms A and C were converted to amorphous CPM in a major portion and Forms C and A, respectively, in a minor portion. The polymorphic transition behavior was clearly reflected in the dissolution rate of CPM, i.e., (1) the dissolution rate was in the order of HP--CyD complex (Form C) Form A, and (2) the dissolution rate of Forms A and C after the compression increased because of the conversion to amorphous state, while the complex maintained the fast dissolving property even after the compression. The results indicated that HP--CyD is useful not only for converting crystalline CPM to an amorphous substance, but also for maintaining the metastable form with fast dissolution rate, Form C, over a long period.     

Microbial transformation of (−)-Huperzine A

Five products were yielded from the transformation of (−)-Huperzine A (1) by Streptomyces griseus CACC 200300. Their structures were determined as 16-hydroxyl huperzine A (2), 14α-hydroxyl huperzine A (3), huperzine A 8α,15α-epoxide (4), 13N-formyl huperzine A (5), and 13N-acetyl huperzine A (6) on the basis of their chemical and physical data. It is the first report on the microbial transformation of (−)-Huperzine A and would facilitate further structural modification by chemo-enzymatic method.     

Chelation and radiolytic determination of lanthanides with 2,2′-oxybis-[ethyliminodi/acetic/ acid]

A quantitative study of the interaction of some lanthanide ions with 2,2-oxybis-[ethyliminodi /acetic/ acid] or 2,2-bis [aminoethyl]ether-tetraacetic acid /BAETA/ was carried out. Stability constants of the lanthanide chelates containing 11 ratio of metal to ligand were determined. A discussion of the variation of the metal chelates stability constants in the lanthanide series is given. Radiolysis of the formed chelates has also been investigated both in presence and in absence of oxygen. A radiolytic degradation mechanism is proposed and discussed.     

ANTIBACTERIAL ACTIVITY OF SINGLE AND MIXED AMMONIUM AND PHOSPHONIUM SALTS GRAFTED ON "GEL-TYPE" STYRENE-DIVINYLBENZENE COPOLYMERS*

1.INTRODUCTIONThesynthesisofpolymer-supported"onium"salts(ammoniumandphosphonium)(1~5(wasdiscussedindetailduetothewidefieldofutilizationas:polarstationaryphasesforanionchromatography(6(,polymericreagentsfortrans-quaternizationreactions(7,8(,phase-transfercatalysts(9~13(andpolycationicbiocides(14~17(.Manychemicalmaterialssuchasozone,liquidchlorine,sodiumhydrochloride,s.a.,havebeenlargelyusedtosterilizeairandwater.Suchmaterialsrequirespecialequipmentandcarelessusemaycauseenvironmentalpolluti…     

“改进的棱柱形”优化系统在高效液相色谱中的建立和应用 Ⅰ.“棱柱形”溶剂强度优化系统的改进

本文建立了适于高效液相色谱的“Improved-PRISMA”优化系统,利用全范田二元线性梯度淋洗进行溶剂强度的优化,只需一次实验即可得知所需溶剂的最佳强度,简化了原“PRISMA”系统选择溶剂强度的过程。将此系统用于七个有机磷化合物的分离,得到了满意的结果。