bluuebunny/crossref_metadata_2025 huggingface dataset:
Regioselective end‐functionalization of polylactide oligomers with D‐glucose and D‐galactose
Authors: Bernard Katty , Degée Philippe , Dubois Philippe
Published: February 2003

D‐glucose and D‐galactose end‐functionalized polylactide oligomers were synthesized by controlled ring‐opening polymerization of lactide using aluminium triisopropoxide, triethylaluminium or stannous octoate as promoter. Accordingly, two selectively protected monosaccharides were studied as co‐initiators, either 1,2;5,6‐di‐O‐isopropylidene‐α‐D‐glucofuranose (1) and 1,2;3,4‐di‐O‐isopropylidene‐α‐D‐galactopyranose (2). In contrast to what is known in polymerization of ϵ‐caprolactone, both protected monosaccharides proved to be efficient co‐initiators and yielded end‐functionalized polylactide chains with controlled regioselectivity (C‐3 or C‐6 linkage), predictable molecular weights and narrow molecular weight distributions.

© 2003 Society of Chemical Industry
Polyurethane and sulfonated polysulfone blend ultrafiltration membranes: II. Application studies
Authors: Malaisamy Ramamoorthy , Mohan Doraiswamy Raju , Rajendran Munnuswamy
Published: February 2003

Ultrafiltration membranes are largely being applied for macromolecular and heavy metal ion separations from aqueous streams. Polyurethane‐ and sulfonated‐ polysulfone‐based membranes prepared in the absence and presence of the polymeric additive, poly(ethylene glycol) 600, in various compositions, were subjected to the rejection of macromolecular proteins, such as bovine serum albumin, egg albumin, pepsin and trypsin. Toxic heavy metal ions such as Cu2+, Ni2+, Cd2+ and Zn2+ were subjected to rejection by the blend membranes by complexing them with a polymeric ligand, polyethyleneimine. The effects of polymer blend compositions and additive concentrations on the rejection and permeate flux of both proteins and metal ions are discussed. The rejection and permeate flux efficiencies of the blend membranes are compared with pure sulfonated polysulfone membranes.

© 2003 Society of Chemical Industry
On the stereochemical composition of poly(vinyl chloride) (PVC) and polypropylene (PP): a phenomenological study
Authors: Guarrotxena Nekane , Schue François , Collet André , Millán José‐Luis
Published: February 2003

The number of mmr‐ and rrm‐based structures which occur necessarily whenever an isotactic or a syndiotactic sequence breaks off respectively; the extent to which they are isolated or are extended to atactic sequences, and the fact that the mmr repeating sequence, especially when it takes the GTTG−TT conformation, is shorter and exhibits greater local free volume than rrm, mmm and rrr sequences, are shown to be the stereochemical composition determining structures in poly(vinyl chloride) (PVC) and polypropylene (PP) polymers. These structures, as analyzed by 13C NMR spectroscopy and probability calculations, have been determined as a function of the overall tacticity for one series of samples prepared by bulk polymerization at temperatures varying from −50 °C to 70 °C, and one series of samples prepared by polarity‐based fractionation of a commercial polymer. Using this approach, the stereochemical composition of the samples could be identified. The results are of interest to understand the changes in the physical properties as shown in earlier and current work for both series of polymers.

© 2003 Society of Chemical Industry
Characteristics of polyimide ultrafine fibers prepared through electrospinning
Authors: Nah Changwoon , Han Sang Hyub , Lee Myong‐Hoon , Kim Jong Sang , Lee Dai Soo
Published: February 2003

A novel route for making polyimide sub‐micron fibers is described. The ultrafine fibers are prepared by electrospinning a poly(amic acid) solution, a precursor of polyimide, followed by thermal imidization. The fiber diameters, which are much smaller than conventionally spun fibers, range from a few tens of nanometers to several micrometers. A rectangular cross‐section is observed in the case of sub‐micron fibers with a cross‐sectional dimension below ∼500 nm.

© 2003 Society of Chemical Industry
Thermal doping of polyaniline by sulfonic acids
Authors: Poussin Denis , Morgan Huda , Foot Peter J S
Published: February 2003

The thermal doping of the emeraldine base (EB) form of polyaniline using two different sulfonic acids, dodecylbenzene sulfonic acid (DBSA) and p‐toluenesulfonic acid (pTSA) has been studied. Differential scanning calorimetry was used to record thermal events associated with the doping process. EB undergoes thermally induced doping with both acids at temperatures depending on the initial quantity of the dopant present. The doping temperatures show an increasing trend with increasing proportion of acid. The enthalpy of doping is also composition dependent. Conductivity values determined by the four‐probe method are given for each sample. The highest conductivities were attained at a mole ratio of 1 (dopant:EB) for both EB(DBSA) and EB(pTSA).

© 2003 Society of Chemical Industry
Biodegradations of statistical copolymers composed of D,L‐lactide and cyclic carbonates
Authors: Tsutsumi Chikara , Nakagawa Katsuhiko , Shirahama Hiroyuki , Yasuda Hajime
Published: February 2003

Syntheses and biodegradation of statistical copolymers of D,L‐lactide (D,L‐LA) with trimethylene carbonate (TMC), rac‐1‐methyltrimethylene carbonate (1‐MTMC) and 2,2‐dimethyltrimethylene carbonate (2,2‐DTMC) were investigated at various monomer ratios using SmMe(C5Me5)2THF as an initiator at 80 °C for 24 h in toluene. Biodegradations of poly(D,L‐LA‐co‐racemo‐1‐MTMC) (95/5) and poly(D,L‐LA‐co‐2,2‐DTMC) (98/2) with a compost at 60 °C proceed rapidly. Enzymatic degradations of these polymers were also performed using cholesterol esterase, lipoprotein lipase and proteinase K. Only poly(D,L‐LA‐co‐TMC) was biodegraded with cholesterol esterase, while poly(TMC), poly(1‐MTMC), poly(2,2‐DTMC) and poly(D,L‐LA) were barely degraded with these enzymes. Biodegradations of poly(D,L‐LA‐co‐TMC) (87/13) and poly(D,L‐LA‐co‐racemo‐1‐MTMC) (95/5) are rapid using proteinase K. Physical properties of these copolymers were also described.

© 2003 Society of Chemical Industry
Film formation from concentrated reactive silicone emulsion: 3. film structuring
Authors: Guigner Delphine , Fischer Christian , Holl Yves
Published: February 2003

Film formation mechanisms from concentrated emulsions of reactive polydimethylsiloxane in water, stabilized by a polyethoxylated fatty alcohol, were studied. Following Part 1 in this series, devoted to drying mechanisms, and Part 2, to surfactant distribution, this part deals with film structuring. Three layers were observed in the thickness: a top transparent, elastic skin, made of coalesced drops; an intermediate white, non cohesive layer; and a white, cohesive layer in contact with the substrate, containing separate surfactant domains as a dispersed phase. Structuring essentially depends on the local rate of water elimination, which is itself directly connected to the global drying rate. The total amount of surfactant in the emulsion seems also to play a specific role.

© 2003 Society of Chemical Industry
Kinetic and thermodynamic study of methanolysis of poly(ethylene terephthalate) waste powder
Authors: Mishra S , Goje A S
Published: February 2003

Depolymerization of poly(ethylene terephthalate) waste (PETW) was carried out by methanolysis using zinc acetate in the presence of lead acetate as the catalyst at 120–140 °C in a closed batch reactor. The particle size ranging from 50 to 512.5 µm and the reaction time 60 to 150 min required for methanolysis of PETW were optimized. Optimal percentage conversion of PETW into dimethyl terephthalate (DMT) and ethylene glycol (EG) was 97.8% (at 120 °C) and 100% (at 130 and 140 °C) for the optimal reaction time of 120 min. Yields of DMT and EG were almost equal to PET conversion. EG and DMT were analyzed qualitatively and quantitatively. To avoid oxidation/carbonization during the reaction, methanolysis reactions were carried out below 150 °C. A kinetic model is developed and the experimental data show good agreement with the kinetic model. Rate constants, equilibrium constant, Gibbs free energy, enthalpy and entropy of reaction are also evaluated at 120, 130 and 140 °C. The methanolysis rate constant of the reaction at 140 °C (10.3 atm) was 1.4 × 10−3 g PET mol−1 min−1. The activation energy and the frequency factor for methanolysis of PETW were 95.31 kJ mol−1 and 107.1 g PET mol−1 min−1, respectively.

© 2003 Society of Chemical Industry
Synthesis and electroluminescent properties of a novel copolymer with short alternating conjugated and non‐conjugated blocks
Authors: Wang Haiqiao , Sun Qingjiang , Li Yongfang , Duan Lian , Qiu Yong , Li Xiaoyu
Published: February 2003

A new electroluminescent copolymer [poly(1,5‐di(3,5‐dimethyloxystyrylene)naphthalene‐block‐tri(ethylene oxide)) (DSN–TEO)], containing alternating rigid, conjugated light‐emitting units and flexible tri(ethylene oxide) ionic conductive units, was synthesized via the Wittig reaction. The polymer has fairly good solubility in chloroform, tetrahydrofuran, toluene, etc, and excellent film‐forming ability. The decomposition temperature and the glass transition temperature were 409 °C and 42.2 °C, respectively. A light‐emitting diode (LED) device with configuration ITO/PEDOT–PSS/DSN–TEO/Ca(Al) and light‐emitting electrochemical cell (LEC) device with ITO/DSN–TEO + PEO (LiTf)/Al were prepared, and the photoluminescence and electroluminescence (EL) properties were investigated. Efficient blue‐green light emission (EL maximum emissive wavelength at 508 nm) was found with onset voltage at 6 V. The maximum light efficiency was 0.107 cd A−1 at 20 V for LED, and the onset voltage 2.5 V and the maximum light efficiency was 4.2 cd A−1 at 2.8 V for LEC, respectively. The response time of the LEC was less than 5 s. The EL efficiency of LEC device was improved by 44 as compared with the relative LED device.

© 2003 Society of Chemical Industry
Crosslinking of pressure sensitive adhesive based on water‐borne acrylate
Authors: Czech Z
Published: February 2003

This publication shows how the kind of crosslinking agents and their contents influence important properties of acrylic based pressure‐sensitive adhesive (PSA) dispersions such as tack, adhesion and cohesion. Synthesized PSAs based on acrylic polymers, containing 2‐ethylhexyl acrylate, butyl acrylate, vinyl acetate, styrene and acrylic acid are used in the preparation of self‐adhesive dispersions used as coating of polyethylene foams and poly(vinyl chloride) and polyester foils.

© 2003 Society of Chemical Industry
Ultrasonic‐assisted dyeing: I. Nylon dyeability with reactive dyes
Authors: Kamel M M , El‐Shishtawy Reda M , Hanna H L , Ahmed Nahed S E
Published: February 2003

The use of ultrasonic power (38.5 KHz, 350 W) to assist the dyeability of nylon‐6 fibre with reactive dyes is reported. The effects of the different factors that may affect the dyeability of nylon‐6 fibre with Reactive Red 55 were simultaneously carried out under both ultrasonic power and conventional heating conditions. The colour strength values obtained for the dyed samples using ultrasonic power were higher than those obtained using conventional heating. Also, the effect of alkaline soaping treatment on dye fixation for the dyed fabrics with different reactive dyes, at both acidic and neutral pHs, is generally better with ultrasonic than with conventional heating. The overall results indicate that the enhancing effect is mainly attributed to the de‐aggregation of dye molecules, which leads to better dye diffusion and possible assistance for dye‐fibre covalent‐bond fixation. The results of wet fastness properties of the dyed fabrics reveal improvement using ultrasonic power dyeing relative to the conventional heating method.

© 2003 Society of Chemical Industry
Ultrasonic‐assisted dyeing: II. Nylon fibre structure and comparative dyeing rate with reactive dyes
Authors: El‐Shishtawy Reda M , Kamel M M , Hanna H L , Ahmed Nahed S E
Published: February 2003

Comparative dyeing kinetics of nylon‐6 fibre with different reactive dyes using conventional and ultrasonic conditions are presented. The time/dye‐uptake isotherms are revealing the enhanced dye‐uptake in the second phase of dyeing (diffusion phase). The data of dyeing rate fit well with the integrated form of the first‐order rate equation and values of dyeing rate constant and half‐time of dyeing are discussed. Ultrasonic efficiency in accelerating the dyeing rate relative to conventional heating was examined for all dyes used to show that ultrasonics are most effective for a dyeing system which has difficulty in achieving high dye‐uptake. To clarify the role of fibre fine structure and whether it is affected during dyeing with ultrasonic waves, time‐dependent ultrasonic pre‐treatment of nylon‐6 fibres and its effect on the colour strength obtained is presented. X‐ray diffraction studies on nylon‐6 fibres conventionally and ultrasonically pre‐treated have shown that the percentage of fibre crystallinity has become higher in ultrasonically treated fibre in comparison with that of conventionally treated. Although the increased crystallinity of the fibre, which occurs simultaneously during the ultrasonic dyeing process, would retard dye uptake, it seems that the enhanced effect of power ultrasonic is high enough to overcome this side‐effect on the fibre.

© 2003 Society of Chemical Industry
The effect of buffer concentration, pH and buffer ions on the degradation and drug release from polyglycolide
Authors: Hurrell Susan , Cameron Ruth E
Published: February 2003

Samples of polyglycolide were degraded in various buffered solutions in order to investigate the effects of buffer concentration, pH and particular buffer ions on the hydrolysis reaction. The small‐angle X‐ray scattering profiles changed with degradation; long periods were calculated and their changes with degradation used as a measure of the degradation rate. The release of a model drug, theophylline, was also investigated under these different buffering conditions. In more concentrated buffer solutions theophylline was released slightly earlier and the samples began to swell sooner. Increasing the pH of the phosphate buffer also resulted in an earlier swelling and release of drug. These effects were attributed to the neutralisation and increased solubility of acidic degradation products in more concentrated or alkaline buffer solutions. When an imidazole–HCl rather than a phosphate or citrate–citric acid buffer system was used, swelling and drug release were accelerated, as imidazole catalysed the ester hydrolysis reaction. The results are interpreted within the context of a four‐stage model of PGA degradation.

© 2003 Society of Chemical Industry
Microbial screening of copolymers of 2,4‐dichlorophenyl methacrylate with N‐vinylpyrrolidone: synthesis and characterization
Authors: Patel Mitesh B , Patel Dharmesh A , Ray Arabinda , Patel Rajni M
Published: February 2003

Copolymers of 2,4‐dichlorophenyl methacrylate and hydrophilic monomer (N‐vinylpyrrolidone) were synthesized with different feed ratios using dimethylformamide as solvent and 2,2′‐azobisisobutyronitrile as initiator at 70 °C. The copolymers were characterized by IR spectrometry. Copolymer compositions were determined by UV spectrometry. The monomer reactivity ratios were determined by applying the conventional linearization method of Fineman‐Ross. Gel permeation chromatography was employed for determining molecular weights and polydispersity indexes. Thermogravimetric analyses of polymers were carried out in nitrogen atmosphere. Homo‐ and copolymers were tested for their antimicrobial properties against selected microorganisms.

© 2003 Society of Chemical Industry
Modification of the thermal properties and crystallization behaviour of poly(ethylene terephthalate) by copolymerization
Authors: Kint Darwin P R , Muñoz‐Guerra Sebastián
Published: February 2003

Poly(ethylene terephthalate) (PET) is a widely used polyester, which can be crystallized from the melt over a wide range of supercooling conditions or, alternatively, quenched into the amorphous state and, subsequently, crystallized by thermal treatment above the glass‐transition temperature. It is well known that the crystallization of PET can be hindered by means of copolymerization or reactive blending. The incorporation of comonomeric units into the polymer backbone leads to an irregular chain structure and thereby inhibits regular chain packing for crystallization. The crystallization of PET copolyesters is strongly influenced by the chain microstructure regarding comonomer distribution, randomness and length of the crystallizable ethylene terephthalate sequences. This paper is mainly devoted to the thermally induced crystallization behaviour of PET and to reviewing the efforts that have been made in the last decade to modify the glass‐transition and melting temperatures, the crystallinity and the crystallization rate of this polyester. Furthermore, some illustrative experimental data obtained from isothermal and non‐isothermal crystallization of PET are included in this study.

© 2003 Society of Chemical Industry
Synthesis of charged linear and crosslinked maleic diester polymers with electron‐beam irradiation
Authors: Atta Ayman M , Arndt K‐F
Published: February 2003

Series of maleic mono‐ and diester monomers have been prepared by esterification of maleic anhydride with poly(ethylene glycol) having different molecular weights, and with n‐dodecyl alcohol. These monomers were copolymerized with 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) using different dose rates of electron‐beam irradiation ranging from 40 to 150 kGy. The synthesized copolymers were characterized by IR and 1H NMR analysis. Their aggregation behaviour and viscometric properties in aqueous solutions were investigated. The crosslinked copolymers were prepared in aqueous acidic solutions at pH 1 or in the presence of 1% of N,N‐methylene bisacrylamide (MBA) as crosslinking agent. The final equilibrium water content and swelling capacities for the prepared hydrogels were determined in aqueous solutions at pH = 1, 6.8 and 12 at 298 K. Swelling equilibria for the prepared hydrogels were carried out in aqueous solutions of NaCl, KCl, CaCl2, Na2SO4, K2SO4 and CaSO4 at concentrations ranging from 1 × 10−6 to 2 M at 298 K.

© 2003 Society of Chemical Industry
Synthesis and characterization of cationic polymeric salts: derivatives of 2‐(dimethylamino)ethyl‐2‐methacrylate, containing oligomeric ethylene oxide side‐chains
Authors: Stålgren J J R , Pamedytyte V , Makuska R , Claesson P M , Brown W , Jacobsson U
Published: February 2003

A novel set of cationic polyelectrolytes has been prepared. The polyelectrolytes have a high cationicity with each segment carrying one positively charged quaternary ammonium group. The polyelectrolytes also contain grafted oligo(ethylene oxide) (EO) chains. The grafted EO chains are, according to NMR measurements, six units long. The graft density of EO chains has been varied and polymers having approximately 100%, 20% and 10% of the segments with a grafted EO chain have been prepared. The obtained products were characterized using 1H and 13C NMR spectroscopy. Aqueous solutions of the cationic polymers were characterized by dynamic light‐scattering (DLS) measurements. It was found to be important to include a radical inhibitor to prevent crosslinking reactions during isolation and purification. In general the DLS measurements showed a bimodal size distribution. The majority of the polymers (about 75 wt%) were found to have a hydrodynamic radius of 6–8 nm, with the remaining polymers being dominated by a fraction with a hydrodynamic radius in the range 120–140 nm.

© 2003 Society of Chemical Industry
Structure‐efficiency relationships of zwitterionic detergents as protein solubilizers in two‐dimensional electrophoresis
Authors: Tastet Christophe , Charmont Stéphane , Chevallet Mireille , Luche Sylvie , Rabilloud Thierry
Published: February 2003

Several zwitterionic detergents differing in their polar heads, linker parts and hydrophobia tail were synthesized and evaluated for their efficiency in protein solubilizers for two‐dimensional electrophoresis. A model system consisting of human red blood cell ghosts was used for this purpose. This study leads to the description of several new efficient detergents and allowed us to derive structural constraints for the design and synthesis of efficient detergents for two‐dimensional electrophoresis. These constraints apply to the hydrophilic head (sulfobetaine but not carboxybetaine), to the hydrophobic tail (12 to 16 alkyl carbons long, linear alkyl or alkylaryl) and to the presence and nature of the linker between the hydrophilic head and hydrophobic tail.
Peptidomics: A new approach to affinity protein microarrays
Authors: Scrivener Elaine , Barry Richard , Platt Albert , Calvert Robert , Masih George , Hextall Patrick , Soloviev Mikhail , Terrett Jonathan
Published: February 2003

Protein microarrays for diagnostic and proteomic analyses are being developed using a number of different techniques for each of the steps required including immobilisation methods, assay and detection systems. This is extremely different to the development of DNA microarrays which is now a well established technology that has demonstrated the capabilities of transcriptomics to deliver validated differential transcripts. As mRNA and protein levels do not always correlate, protein microarrays would seem to be an obvious successor to DNA arrays. Unlike nucleic acids, however, protein targets are typically nonhomogeneous in physicochemical properties and affinity capture agents are often poorly characterised making the experiments difficult to perfect and reproduce. Moreover, running multiple affinity assays in parallel (multiplexing) is compromised by the heterogeneity of antibody affinities to their protein targets. In the peptidomic approach presented here the assayed mixture of proteins is enzymatically digested prior to affinity capture to form a mixture of short peptides that are more similar in their physicochemical properties than intact proteins. These peptides can be predicted by in silico digestion of individual proteins, e.g. from protein databases allowing design of nonhomologous reagents for the screening of affinity agent libraries. The use of mass spectrometry (e.g. matrix‐assisted laser desorption/ionization‐time of flight mass spectrometry) for a direct confirmation of the identity of the species captured, provides a further advantage compared to the more usual method of detection in which fluorescently labelled captured species are scanned to give a spatially resolved image of the array.
VIRTUAL2D: A web‐accessible predictive database for proteomics analysis
Authors: Medjahed Djamel , Smythers Gary W. , Powell Douglas A. , Stephens Robert M. , Lemkin Peter F. , Munroe David J.
Published: February 2003

The available archive of sequence databases compiled from whole genome projects and budding proteomics efforts have enabled us to develop VIRTUAL2D, an interactive system for the assembly of virtual protein expression maps computed on the basis of theoretical isoelectric focusing point, molecular weight, tissue specificity and relative abundance for any set of proteins currently catalogued. This tool will assist in the preliminary, albeit putative, prediction of the identity and location of unknown and/or low abundance proteins in experimentally derived two‐dimensional polyacrylamide gel electrophoresis maps.
Mass spectrometry analysis of CD4‐associating proteins using affinity chromatography and affinity tag‐mediated purification of tryptic peptides
Authors: Bernhard Oliver K. , Burgess Jennifer A. , Hochgrebe Tim , Sheil Margaret M. , Cunningham Anthony L.
Published: February 2003

The study of protein interactions using mass spectrometry (MS) for identification of the components of purified protein complexes is leading to the description of increasingly valuable data on protein function. Commonly proteins in a given complex are identified via MS analysis of in‐gel digests of gel electrophoretically separated proteins. In this study, we have evaluated the use of an approach employing the digest of the whole protein complex to identify directly the proteins present in a purification of the CD4 receptor complex. We used a cysteinyl affinity capture method to reduce the complexity of the peptide mixture that was obtained from the tryptic digest of the whole protein complex to the rather limited mixture of only cysteine‐containing peptides. Here we report the use of this approach with MS for identification of the CD4 receptor complex components CD4 and p56lck, along with several other proteins present in the detergent‐solubilized fractions from the purification. We have been able to identify these proteins using peptide sequence data obtained from cysteine‐containing peptides. With appropriate control experiments, we have demonstrated the specific nature of the CD4‐p56lck interaction. In contrast, the other proteins identified are shown to arise from nonspecific interactions during the affinity chromatography purification suggesting a possible loss of specific interactions during the chromatography procedure. We found that the complexity of the mixture was reduced such that only 10% of the peptides derived from tryptic digest of the identified proteins were detected. This represents only one‐third of the cysteine‐containing peptides, however, suggesting that this approach does not enable detection of all individual proteins.
Identification of cellular changes associated with increased production of human growth hormone in a recombinant Chinese hamster ovary cell line
Authors: Van Dyk Derek D. , Misztal David R. , Wilkins Marc R. , Mackintosh James A. , Poljak Anne , Varnai Jodie C. , Teber Erdahl , Walsh Bradley J. , Gray Peter P.
Published: February 2003

A proteomics approach was used to identify the proteins potentially implicated in the cellular response concomitant with elevated production levels of human growth hormone in a recombinant Chinese hamster ovary (CHO) cell line following exposure to 0.5 mM butyrate and 80 μM zinc sulphate in the production media. This involved incorporation of two‐dimensional (2‐D) gel electrophoresis and protein identification by a combination of N‐terminal sequencing, matrix‐assisted laser desorption/ionisation‐time of flight mass spectrometry, amino acid analysis and cross species database matching. From these identifications a CHO 2‐D reference map and annotated database have been established. Metabolic labelling and subsequent autoradiography showed the induction of a number of cellular proteins in response to the media additives butyrate and zinc sulphate. These were identified as GRP75, enolase and thioredoxin. The chaperone proteins GRP78, HSP90, GRP94 and HSP70 were not up‐regulated under these conditions.
Progress in the definition of a reference human mitochondrial proteome
Authors: Lescuyer Pierre , Strub Jean‐Marc , Luche Sylvie , Diemer Hélène , Martinez Pascal , Van Dorsselaer Alain , Lunardi Joël , Rabilloud Thierry
Published: February 2003

Owing to the complexity of higher eukaryotic cells, a complete proteome is likely to be very difficult to achieve. However, advantage can be taken of the cell compartmentalization to build organelle proteomes, which can moreover be viewed as specialized tools to study specifically the biology and “physiology” of the target organelle. Within this frame, we report here the construction of the human mitochondrial proteome, using placenta as the source tissue. Protein identification was carried out mainly by peptide mass fingerprinting. The optimization steps in two‐dimensional electrophoresis needed for proteome research are discussed. However, the relative paucity of data concerning mitochondrial proteins is still the major limiting factor in building the corresponding proteome, which should be a useful tool for researchers working on human mitochondria and their deficiencies.
Diversity of puroindolines as revealed by two‐dimensional electrophoresis
Authors: Branlard Gérard , Amiour Nardjis , Igrejas Gilberto , Gaborit Thérèse , Herbette Stephane , Dardevet Mireille , Marion Didier
Published: February 2003

Puroindolines are endosperm lipid binding proteins, which are separated by reversed phase‐high‐performance liquid chromatography or cation exchange chromatography into two isoforms, puroindoline‐a (PIN‐a) and puroindoline‐b (PIN‐b). Being very basic and close in molecular weight, PIN‐a and PIN‐b have never been separated using conventional isoelectric focusing and sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE). A two‐dimensional electrophoresis method, linear immobiline pH gradient (IPG×SDS‐PAGE), was developed, using 6–11 linear immobiline Dry Strips in the first dimension, which allowed the puroindolines to be focused between isoelectric point 10.5 and 11. Immunoblotting revealed that both PIN‐a and PIN‐b were each composed of several spots. Two‐dimensional patterns from unrelated wheat varieties revealed that several spots can be highlighted among varieties. Matrix‐assisted laser desorption/ionization‐time of flight spectrometry allowed the majority of the spots revealed in the puroindoline zone to be identified. The two‐dimensional IPG×SDS‐PAGE of these very basic wheat endosperm proteins, puroindolines and related grain softness proteins should facilitate the identification of the proteins associated with wheat endosperm texture that have a strong effect on milling, dough properties and end‐uses of wheats.
Proteomic analysis of the effect of heat stress on hexaploid wheat grain: Characterization of heat‐responsive proteins from total endosperm
Authors: Majoul Thouraya , Bancel Emmanuelle , Triboï Eugène , Ben Hamida Jeannette , Branlard Gérard
Published: February 2003

High temperatures during grain filling have been reported to be one of the factors that can affect the dough properties and quality characteristics of wheat. Responses to high temperature have been related to changes in protein composition at both quantitative and qualitative levels. The present study was conducted to determine the influence of high temperature during grain filling on the protein composition of bread wheat evaluated by proteomic tools. Plants were grown in the field and transferred to cabinets soon after flowering. They were subjected to two thermal regimes 18°C/10°C (day/night) and 34°C/10°C. Total proteins were extracted from control grains and treated plants at three different post‐anthesis stages. The proteins were separated by two‐dimensional gel electrophoresis and analysed by Melanie 3 software. Of the total number of mature wheat grain proteins, 37 were identified as significantly changed by heat treatment. Analysis by matrix‐assisted laser desorption/ionization mass spectrometry and tandem mass spectrometry coupled with database searching allowed the characterization of 25 heat‐induced proteins and only one heat‐decreased protein spot. To learn more about the function of the identified proteins, we examined their expression during treatment.
Protein identification in cerebrospinal fluid using packed capillary liquid chromatography Fourier transform ion cyclotron resonance mass spectrometry
Authors: Ramström Margareta , Palmblad Magnus , Markides Karin E. , Håkansson Per , Bergquist Jonas
Published: February 2003

The identification and characterization of proteins in complex biological samples such as body fluids, require powerful and reliable tools. Mass spectrometry is today one of the most important methods in such research. This paper reports on the results from the first experiment where a tryptic digest of cerebrospinal fluid was analyzed applying reversed phase liquid chromatography coupled on‐line to a 9.4 T Fourier transform ion cyclotron resonance mass spectrometer. In total, 70 204 peaks were detected, which originated from 16 296 isotopic clusters corresponding to 6551 unique peptide masses. From these masses, 39 proteins were identified in the sample. The amount of sample required for one experiment corresponds to 32 μL of cerebrospinal fluid.
Protein expression profiling of glutathione S‐transferase pi null mice as a strategy to identify potential markers of resistance to paracetamol‐induced toxicity in the liver
Authors: Kitteringham Neil R. , Powell Helen , Jenkins Rosalind E. , Hamlett Jane , Lovatt Cerys , Elsby Robert , Henderson Colin J. , Wolf C. Roland , Pennington Stephen R. , Park B. Kevin
Published: February 2003

GST pi (GSTP) is a member of the glutathione S‐transferase (EC 2.5.1.18; GST) family of enzymes that catalyse the conjugation of electrophilic species with reduced glutathione and thus play an important role in the detoxification of electrophilic metabolites. Deletion of GSTP in mice has previously been shown to lead to enhanced susceptibility to chemical‐induced skin carcinoma, consistent with its known metabolic functions. A decreased susceptibility to paracetamol hepatotoxicity has also been observed, which has not been fully explained. One possibility is that deletion of the GSTP gene locus results in compensatory changes in other proteins involved in defence against chemical stress. We have therefore used complementary protein expression profiling techniques to perform a systematic comparison of the protein expression profiles of livers from GSTP null and wild‐type mice. Analysis of liver proteins by two‐dimensional electrophoresis confirmed the absence of GSTP in null mice whereas GSTP represented 3–5% of soluble protein in livers from wild‐type animals. There was a high degree of quantitative and qualitative similarity in other liver proteins between GSTP null and wild‐type mice. There was no evidence that the absence of GSTP in null animals resulted in enhanced expression of other GST isoforms in the null mice (GST alpha, 1.48%, GST mu, 1.68% of resolved proteins) compared with the wild‐type animals (GST alpha, 1.50%, GST mu, 1.40%). In contrast, some members of the thiol specific antioxidant family of proteins, notably antioxidant protein 2 and thioredoxin peroxidases, were expressed at a higher level in the GSTP null mouse livers. These changes presumably reflect the recently described role of GSTP in cell signalling and may underlie the protection against paracetamol toxicity seen in these animals.
Hyperubiquitination of proteins in dilated cardiomyopathy
Authors: Weekes John , Morrison Karen , Mullen Anthony , Wait Robin , Barton Paul , Dunn Michael J.
Published: February 2003

Protein degradation by the ubiquitin‐proteasome pathway plays an important role in a variety of fundamental cellular processes, including cell cycle regulation, transcription, antigen processing and muscle remodelling. Research into disorders associated with the ubiquitin‐proteasome system has been mainly in the field of neurodegenerative diseases. It is however becoming increasingly apparent that defects in the system are responsible for a number of non‐neurological pathologies. Based on initial observations made as part of a proteomic analysis of an animal model of dilated cardiomyopathy (DCM) which indicated increased activity of the ubiquitin‐proteasome system, we sought to determine whether this system was perturbed in hearts of human DCM patients. We studied explanted hearts from 12 DCM, 9 ischaemic (IHD) and 12 unused donor hearts. Protein expression was examined using two‐dimensional polyacrylamide gel electrophoresis, Western blotting and immunohistochemistry. Expression of mRNA was examined using real‐time quantitative polymerase chain reaction. Ubiquitinated proteins were affinity purified using a ubiquitin‐binding column and identified using peptide mass fingerprinting. All DCM hearts showed significantly higher expression of certain key enzymes of the ubiquitin‐proteasome pathway. mRNA expression of ubiquitin carboxyl‐terminal hydrolase (UCH) was significantly higher (5.4‐fold) in DCM hearts than in control hearts. Myocytes in sections from DCM hearts stained positively for UCH, whereas control hearts were negative. Overall protein ubiquitination was increased two‐fold in DCM relative to IHD hearts and five‐fold relative to donor hearts. The ubiquitination of a number of distinct proteins was greatly enhanced in DCM hearts as revealed by anti‐ubiquitin Western blots. A number of these proteins were identified using affinity purification and matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry.
Novel subunits of the TATA binding protein free TAFII‐containing transcription complex identified by matrix‐assisted laser desorption/ionization‐time of flight mass spectrometry following one‐dimensional gel electrophoresis
Authors: Cavusoglu Nükhet , Brand Marjorie , Tora Laszlo , Van Dorsselaer Alain
Published: February 2003

Initiation of transcription of protein‐encoding genes by RNA polymerase II was thought to require the transcription factor II D (TFIID), a complex comprising the TATA binding protein (TBP) and TBP‐associated factors. However, another multiprotein complex isolated more recently and called TFTC (TBP‐free TAFII containing complex), was shown to mediate initiation of RNA polymerase II (Pol II) transcription in the absence of TFIID as well as specific acetylation of histone H3 in a nucleosomal context. Several subunits of the TFTC complex were already identified using classical methods such as Edman based microsequencing and Western blot analysis. In this article we present a mass spectrometry based proteomic approach to confirm previous results and to identify other possible subunits of the TFTC complex. The TFTC complex was separated on one‐dimensional sodium dodecyl sulfate polyacrylamide electrophoresis and analysed by matrix‐assisted laser desorption/ionization‐time of flight mass spectrometry and peptide mass fingerprinting. Identifications were realized after databank searches. This new characterization of TFTC complex confirmed the presence of already described subunits (TRRAP, GCN5, SAP130/KIA0017, TAFII150, TAFII135, TAFII100, TAFII80, TAFII20, SPT3 and PAF65β). Moreover, a good coverage of these sequences was obtained. Interestingly, TAFII32 and PAF6α were also determined as potential novel subunits of TFTC. These results together show the suitability and the great potential of this method and offer new perspectives in fundamental studies of transcription factor complexes.
Proteome analysis of the plant pathogen Xylella fastidiosa reveals major cellular and extracellular proteins and a peculiar codon bias distribution
Authors: Smolka Marcus Bustamante , Martins Daniel , Winck Flavia Vischi , Santoro Carlos Eduardo , Castellari Rafael Ramos , Ferrari Fernanda , Brum Itaraju Junior , Galembeck Eduardo , Della Coletta Filho Helvécio , Machado Marcos Antonio , Marangoni Sergio , Novello Jose Camillo
Published: February 2003

The bacteria Xylella fastidiosa is the causative agent of a number of economically important crop diseases, including citrus variegated chlorosis. Although its complete genome is already sequenced, X. fastidiosa is very poorly characterized by biochemical approaches at the protein level. In an initial effort to characterize protein expression in X. fastidiosa we used one‐ and two‐dimensional gel electrophoresis and mass spectrometry to identify the products of 142 genes present in a whole cell extract and in an extracellular fraction of the citrus isolated strain 9a5c. Of particular interest for the study of pathogenesis are adhesion and secreted proteins. Homologs to proteins from three different adhesion systems (type IV fimbriae, mrk pili and hsf surface fibrils) were found to be coexpressed, the last two being detected only as multimeric complexes in the high molecular weight region of one‐dimensional electrophoresis gels. Using a procedure to extract secreted proteins as well as proteins weakly attached to the cell surface we identified 30 different proteins including toxins, adhesion related proteins, antioxidant enzymes, different types of proteases and 16 hypothetical proteins. These data suggest that the intercellular space of X. fastidiosa colonies is a multifunctional microenvironment containing proteins related to in vivo bacterial survival and pathogenesis. A codon usage analysis of the most expressed proteins from the whole cell extract revealed a low biased distribution, which we propose is related to the slow growing nature of X. fastidiosa. A database of the X. fastidiosa proteome was developed and can be accessed via the internet (URL: www.proteome.ibi.unicamp.br).
Synthetic peptides mimicking the interleukin‐6/gp 130 interaction: a two‐helix bundle system. Design and conformational studies
Authors: Zaccaro Laura , Bucci Enrico , Vitale Rosa Maria , Perretta Giuseppe , Fattorusso Roberto , Benedetti Ettore , Saviano Michele , Pedone Carlo
Published: February 2003

The objective of our study was to mimic in a typical reductionist approach the molecular interactions observed at the interface between the gp 130 receptor and interleukin‐6 during formation of their complex. A peptide system obtained by reproducing some of the interleukin‐6/gp 130 molecular interactions into a two‐helix bundle structure was investigated. The solution conformational features of this system were determined by CD and NMR techniques. The CD titration experiments demonstrated that the interaction between the designed peptides is specific and based on a well‐defined stoichiometry. The NMR data confirmed some of the structural features of the binding mechanism as predicted by the rational design and indicated that under our conditions the recognition specificity and affinity can be explained by the formation of a two‐helix bundle. Thus, the data reported herein represent a promising indication on how to develop new peptides able to interfere with formation of the interleukin‐6/gp 130 complex. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
Oligopeptide‐mediated helix stabilization of model peptides in aqueous solution
Authors: Maeda Yoshitaka , Nakagawa Terumichi , Kuroda Yoshihiro
Published: February 2003

Oligopeptide‐mediated helix stabilization of peptides in hydrophobic solutions was previously found by NMR and CD spectroscopic studies. The oligopeptide included the hydrophobic amino acids found in its parent peptide and were interposed by relevant basic or acidic amino acids. The strength of the interactions depended on the amino acid sequences. However, no helix‐stabilizing effect was seen for the peptides in phosphate buffer solution, because the peptides assumed a random‐coil structure. In order to ascertain whether the helix‐stabilizing effect of an oligopeptide on its parent peptide could operate in aqueous solution, model peptides EK17 (Ac‐AEAAAAEAAAKAAAAKA‐NH2) and IFM17 (Ac‐AEAAAAEIFMKAAAAKA‐NH2) that may assume an α‐helix in aqueous solutions were synthesized. Interactions were examined between various oligopeptides (EAAAK, KAAAE, EIFMK, KIFME, KIFMK and EYYEE) and EK17 or IFM17 in phosphate buffer and in 80% trifluoroethanol (TFE)–20% H2O solutions by CD spectra. EAAAK had little effect on the secondary structures of EK17 in both buffer and TFE solutions, while KAAAE, which has the reverse amino acid sequence of EAAAK, had a marked helix‐destabilizing effect on EK17 in TFE. EIFMK and KIFME were found to stabilize the α‐helical structure of EK17 in phosphate buffer solutions, whereas KIFMK and EYYEE destabilized the α‐helical structure of EK17. EIFMK and KIFME had no effect on IFM17, because unexpectedly, IFM17 had appreciable amounts of β‐sheet structure in buffer solution. It was concluded that in order for the helix‐stabilizing effects to operate effectively, the following factors should be satisfied: (1) the model peptide, the α‐helical conformation of which is to be stabilized, should essentially assume an α‐helical structure by nature, and (2) the hydrophobicity of the side‐chains of the oligopeptide should be high enough for the oligopeptide to perform stable specific side chain–side chain intermolecular hydrophobic interactions with the model peptide. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
Isolation of Vulgin, a New Antifungal Polypeptide with Mitogenic Activity from the Pinto Bean
Authors: Ye X. Y. , Ng T. B.
Published: February 2003

An antifungal polypeptide bearing an N‐terminal sequence with some homology to chitinases was purified from an extract of pinto beans. The polypeptide, designated vulgin, exerted antifungal activity toward Mycosphaerella arachidicola, Coprinus comatus, Fusarium oxysporum and Botrytis cinerea. Vulgin inhibited translation in a rabbit reticulocyte lysate system with an IC50 of 4.3 µM and HIV‐1 reverse transcriptase activity with an IC50 of 58 µM. Vulgin stimulated in vitro incorporation of methyl [3H] thymidine into mouse splenocytes. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
Purification and characterization of a new ribonuclease from fruiting bodies of the oyster mushroom Pleurotus ostreatus
Authors: Ye X. Y. , Ng T. B.
Published: February 2003

A ribonuclease (RNase), possessing an N‐terminal sequence disparate from those of ribonucleases from other mushrooms and previously isolated Pleurotus ostreatus RNases, was purified from the fruiting bodies of the edible mushroom Pleurotus ostreatus. The N‐terminal sequence of Pleurotus ostreatus RNase did not manifest homology even to a previously reported RNase from the same mushroom. The ribonuclease was adsorbed on CM‐Sepharose and Mono S. It exhibited a molecular mass of 12 kDa in both sodium dodecyl sulphate‐polyacrylamide gel electrophoresis and gel filtration on Superdex 75. The ribonuclease displayed an activity of 11 490 U/mg on yeast tRNA. The highest ribonuclease activity was exhibited toward poly U, followed by poly A and poly C. No activity was shown toward poly G. The optimal pH for its activity was 7 and the optimal temperature was 55°C. It inhibited cell‐free translation in a rabbit reticulocyte lysate with an IC50 of 240 nM. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
Synthesis and circular dichroism study of the human salivary proline‐rich protein IB7
Authors: Simon Cécile , Pianet Isabelle , Dufourc Erick J.
Published: February 2003

The solid phase synthesis of a 59 amino acid human salivary protein IB7 has been accomplished using Fmoc strategy. Because the protein contains 25 proline, 13 glycine and 9 glutamine residues the coupling time, piperidine delivery and acetic anhydride reaction time were increased. Yield after HPLC purification was 35%. Circular dichroism studies revealed that about one third of IB7 residues adopted a type II helix secondary structure, as found in collagen helices. The rest of the sequence adopts a random coil secondary structure. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
Surface plasmon resonance spectroscopy in the study of membrane‐mediated cell signalling
Authors: Mozsolits Henriette , Thomas Walter G. , Aguilar Marie‐Isabel
Published: February 2003

Peptide–membrane interactions contribute to many important biological processes such as cellular signalling, protein trafficking and ion‐channel formation. During receptor‐mediated signalling, activated intracellular signalling molecules are often recruited into receptor‐induced signalling complexes at the cytoplasmic surface of the cell membrane. Such recruitment can depend upon protein–protein and protein–lipid interactions as well as protein acylation. A wide variety of biophysical techniques have been combined with the use of model membrane systems to study these interactions and have provided important information on the relationship between the structure of these proteins involved in cell signalling and their biological function. More recently, surface plasmon resonance (SPR) spectroscopy has also been applied to the study of biomembrane‐based systems using both planar mono‐ or bilayers or liposomes. This article provides an overview of these recent applications, which demonstrate the potential of SPR to enhance our molecular understanding of membrane‐mediated cellular signalling. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.