bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental characterization of adsorbed macromolecule layers at solid/liquid interfaces
Authors: Killmann Erwin 
Published: March 2011

AbstractA survey will be given on the experimental methods to characterize the structure of adsorbed polymer layers at solid/liquid interfaces. Characterization parameters accessible by experimental methods are: adsorption isotherm mostly determined from the difference in the solution concentration; fraction of adhered segments, obtained from IR‐, NMR‐ ESR‐spectrometry and from microcalorimetry; layer thicknesses of different type from ellipsometry, diffusion, sedimentation, viscosimetry, electrophoresis, force‐distance measurements between contacting layers and from segment density profiles obtained by SANS; adsorption enthalpies from microcalorimetry and from displacer‐technique. Own experimental data of the adsorption of olystyrene, poly(ethylene oxide)s (PHD), poly(N‐vinyl‐2‐pyrrolidone), poly‐(butyl methacrylate)s, poly(vinyl alcohol)s as well as copolymers from ethylene oxide and propylene oxide on interfaces of colloidal silica‐ and latexparticles and partially on flat chromium‐, platinum‐and gold surfaces from organic and aqueous solutions and characteristic results from the literature will be compared and discussed in order to get insight into the conformation of the adsorbed macromolecules.
Dynamic behaviour of hydrosoluble polymers at a solid/liquid interface
Authors: Varoqui Raphael , Pefferkorn Emile 
Published: March 2011

AbstractThe behaviour of flexible hydrosoluble polymers of high molecular weight: polyacrylamide and two polyacids, poly(α, L‐glutamic acid) and a copolymer of maleic acid was investigated in the context of their dynamic behaviour at solid/liquid interfaces. The adsorption rate is related to the structure of the surface in terms of remaining interacting surface sites. The desorption rate was measured by carrying out adsorption with radioactive labelled polymers, followed by exchange with unlabelled polymers. The slow exchange rate observed suggests a metastable equilibrium state owing to strong multisegment adsorption in the potential well of the surface. However, the “diffuse” polymer layer formed by loops which extend in the aqueous phase within distances of several hundred Angstroms “responds” reversibly to a change in the solvent composition. The latter effect was found by recording the hydrodynamic permeability of pores covered by the adsorbed polymer; the permeability to fluid flow is very sensitive to the loop layer thickness.
Adsorption kinetics of protein mixtures. A tentative explanation of “the vroman effect”
Authors: Cuypers Peter A. , Willems George M. , Hemker H. Coenraad , Hermens Wim Th. 
Published: March 2011

AbstractA model for protein adsorption kinetics is presented. This model includes diffusion limited adsorption, adsorption and desorption rate constants which are dependent on the surface concentration and an interaction term for the mutual influence of the adsorbed protein molecules. It is shown that, in first approximation, the values of the adsorption and desorption rate constants are exponential functions of the surface concentration. Assuming an adequate interaction term it is possible to show with this model for the adsorption kinetics of a mixture of proteins that the ratio of the adsorbed proteins is strongly dependent on the overall surface concentration even if the ratio of the bulk concentrations of these proteins is kept constant. Differences in interaction terms for the different proteins offer a possible explanation for the peculiar behaviour of plasma protein adsorption on a surface at different dilutions of the plasma, the so called “Vroman effect”.
Biospecific complex formation as a tool for oriented immobilization
Authors: Turková J. , Fusek M. , Štovičková J. , Králová Z. 
Published: March 2011

AbstractThe formation of biospecific complexes between the carbohydrate moieties localized on the surface of enzyme molecules and lectins (Hsiao and Royer, Ref.3) or between the appropriate antigenic portions of peptide chains and antibodies (Solomon et al., Ref. 18) permits oriented immobilization to be carried out which makes the catalytic site of the immobilized enzyme perfectly accessible. We have performed such oriented immobilization with carboxypeptidase Y which was attached to concanavalin A ‐ Spheron. On the basis of the results of biospecific affinity chromatography of a conjugate of catalase and dextran carried out by Marshall and Humphreys (Ref. 14) on concanavalin A ‐ Sepharose we prepared active conjugate of chymotrypsin with various dextrans for our investigation of immobilization of chymotrypsin through a bound polysaccharide.The experiments carried out by Solomon et al. (Ref. 18) with the immobilization of carboxypeptidase A via a complex of the enzyme with a suitable monoclonal antibody against carboxypeptidase A showed that the immobilized enzyme had the kinetic properties of native carboxypeptidase A. was more stable and could be used several times. Anti‐chymotrypsin immunoglobulin G(IgG)1 suitable for analogous oriented immobilization of chymotrypsin was isolated from a polyclonal pig antibody against diiso‐propylphosphoryl‐(DIP)‐chymotrypsin by biospecific affinity chromatography on a Sepharose column to which chymotrypsin had been attached through a covalent bond between the surface part of the molecule around the active site and immobilized antilysine, a naturally occurring polyvalent trypsin inhibitor.
New phase supports for partition chromatography of biopolymers
Authors: Müller Werner 
Published: March 2011

AbstractLiquid‐liquid partition chromatography of bio‐polymers requires aqueous two‐phase systems for reasons of sample solubility and stability. Such aqueous two‐phase systems form when thermodynamically incompatible polymers are co‐dissolved in water. The most common polymer combination providing a two‐phase system at reasonably low polymer concentrations is the combination of poly(ethylene glycol) (“PEG”) and dextran (“DX”), detected and introduced for the separation of biopolymers and cells by Albertsson about 30 years ago. The application of this powerful system for liquid‐liquid partition chromatography requires support materials with surfaces able to immobilize selectively one of the two aqueous phases. This phase immobilisation may be achieved by exploiting incompatibilities between the polymers dominating in the phases and the hydrated support surface.Examples involving diol‐modified silica and polyacrylamide coated diol‐silica as support materials in aqueous PEG‐DX and PEG‐salt systems are presented. The application of such systems for the separation of biopolymers is demonstrated.
Current development of analytical affinity chromatography: Design and biotechnological uses of molecular recognition surfaces
Authors: Chaiken Irwin M. , Shai Yechiel , Fassina Giorgio , Caliceti Paolo 
Published: March 2011

AbstractAnalytical high performance liquid affinity chromatography (analytical HPLAC) has been investigated as an experimental guide to both synthetic design and affinity technological use of peptide and protein recognition surfaces. This work has progressed from the ongoing use of analytical affinity chromatography to study interaction mechanisms of naturally‐occurring peptides and proteins, including enzyme fragment complexes and neuroendocrine biosynthetic precursors. We recently initiated a study to use analytical HPLAC for de novo design of recognition peptides called “anti‐sense peptides”. Present data suggest the potential to use anti‐sense peptides as “synthetic antibodies”, in immobilized forms, for biomolecular separation and analysis. Analogous studies have been started with immobilized natural antibodies in analytical immuno HPLAC. Our present data typify the growing usefulness of analytical HPLAC when designing recognition molecules, analyzing their interaction characteristics, and devising ways to use them in affinity technology.
Selective isolation of C‐terminal peptides from proteolytic mixtures of proteins by affinity chromatography on immobilized anhydrotrypsin and anhydrochymotrypsin
Authors: Ishii Shin‐ichi , Kumazaki Takashi , Fujitani Asamichi , Terasawa Kumiko 
Published: March 2011

AbstractAnhydrotrypsin in an immobilized form shows strong specific affinity for the peptides containing Arg, Lys, or S‐aminoethyl‐Cys at their C‐termini. By taking advantage of this unique property of the adsorbent, we established an efficient chromatographic procedure useful for selective isolation of C‐terminal peptides from protease digests of proteins. The utility was demonstrated in cases of a tryptic digest of Streptomyces subtilisin inhibitor in a reduced and S‐carboxymethylated form (RCM‐SSI) (with C‐terminal Phe) and of a chymotryptic digest of α1‐antitrypsin (with C‐terminal Lys): the C‐terminal peptides were recovered as the breakthrough fraction of the chromatography in the former case and as the adsorptive fraction in the latter. Immobilized anhydrochymotrypsin was also useful for selective adsorption of the C‐terminal peptide from the tryptic digest of RCM‐SSI. It was further found that immobilized anhydrotrypsin exerts strong affinity even for human oxyhemoglobin and its α‐chain (with C‐terminal Arg), but not for the β‐chain (with C‐terminal His) and hemoglobin‐haptoglobin complex. Thus the adsorbent may be applicable also to the isolation of macromolecular ligands and to the analysis of macromolecular interactions.
Immobilized metal ion affinity chromatography of proteins on IDA‐Fe3+
Authors: Sulkowski Eugene 
Published: March 2011

AbstractSeveral proteins, selected for their varied isoelectric points within pH range ca. 4 to ca. ll, bind to immobilized (chelated to iminodiacetate) ferric ion, IDA‐Fe3+, when applied in a 50 mM buffer, pH 6.0. These proteins can be displaced from IDA‐Fe3+ columns by an increase of pH from 6 to 8, an increase of sodium chloride from 0 to 1 Malar and, in particular, by both.Apotransferrins, in contrast to other proteins, are able to scavenge Fe3+ ion from IDA‐Fe3+.Interestingly, two proteins, both quite acidic, behave quite differently on IDA‐Fe3+: α1‐acid glycoprotein (sialic acid) does not bind, whereas phosvitin (phosphate 1) binds avidly.IDA‐Fe3+ sorbent, due to its unusual sorptive properties, represents a new addition of particular significance to the family of chromatographic sorbents available for protein purification.
A new kind of “thiophilic” electron‐donor‐acceptor adsorbent
Authors: Porath Jerker , Oscarsson Sven 
Published: March 2011

AbstractFour simple agarose derivatives have been synthesized: 3‐(Z‐pyridylsulfido)‐2‐hydroxypropyl‐ 3‐(2‐pyridyloxy)‐2‐hydroxypropyl‐ 3‐(phenylsulfido)‐2‐hydroxypropyl‐, and 3‐(phenyloxy)‐2‐hydroxypropylagarose. Their affinities for serum proteins have been studied in the presence and absence of water‐structuring salt. About 50% of the proteins, among them immunoglobulins and α2‐macroglobulin, but not albumin, were non‐covalently adsorbed to the PyS‐gel in buffer containing 0.5 M K2SO4. These proteins are the same as those adsorbed to the so‐called thiophilic gel, T‐gel (5), but there are some additional proteins found in the adsorbate that strongly indicate a specific influence on the protein adsorption exerted by the π‐electron system of the pyridine residue. The thio‐ether sulfur appears to be a necessary structural requirement for the characteristic adsorption behaviour. Thiophilic vs. hydrophobic ligand‐protein interaction is discussed.
Studies on triazine dye‐enzyme interaction by means of affinity partitioning
Authors: Kopperschläger Gerhard , Kirchberger Jürgen , Kriegel Thomas 
Published: March 2011

AbstractAffinity partitioning in aqueous two‐phase systems composed of dextran and polyethylene glycol the latter being partially replaced by dye‐substituted polymer was evaluated for the study of enzyme‐dye interaction. The method was found excellently suited for the recognition of any interaction between a certain enzyme and triazine dyes by determining the actual partition coefficient, K.Two enzymes, intestinal alkaline phosphatase and yeast phosphofructokinase, were studied. Alkaline phosphatase binds more or less specifically to various triazine dyes. A number of substrates but also inorganic phosphate, NAD+ and selected chromophores are competing agents in enzyme‐dye interaction whereas hydrophobic and uncompetitive inhibitors fail to compete with the dye. Thus, information on the chemical nature of the dye‐enzyme interaction was obtained. Affinity partitioning turned out also appropriate to study the structural dynamics of enzymes. This was exemplified on the specific interaction of phosphofructokinase with a number of triazine dyes. A change of the allosteric properties of the enzyme in respect to ATP‐inhibition and its reversibility was indicated by a corresponding alteration of the partition coefficient. The results are discussed in terms of a conformational change of the enzyme.
Protein interactions with solid surfaces following contact with plasma and blood
Authors: Brash John L. 
Published: March 2011

AbstractTwo aspects of blood protein interactions with solid surfaces are discussed. The first is competitive adsorption among the many proteins in the blood. The general factors which determine the composition of the adsorbed layer in any multicomponent protein system are considered and then related to current knowledge of competitive adsorption in blood. The latter pertains largely to the so‐called Vroman effect whereby proteins are adsorbed and displaced from the surface in an ordered sequence. Secondly the possible transformation of adsorbed enzyme precursors into active enzymes by the agency of the surface is discussed. The example of the plasminogen‐plasmin system is used to illustrate this discussion.
Time‐resolved spectroscopic studies on phenyl‐substituted poly(phenylenevinylene)s by picosecond excite‐ and probe technique
Authors: Rentsch Sabine , Stolberg Klaus‐Peter , Opfermann Johannes , Hörhold Hans‐Heinrich 
Published: March 2011

AbstractPhotoinduced picosecond absorption spectra of poly(1,4‐phenylene‐1,2‐diphenylvinylene) (DP‐PPV) and of related oligomeric and polymeric compounds were investigated in toluene solution. Between 400 and 900 nm the rise (5 … 40 ps) and decay (40 … 300 ps) of three transient absorption bands have been observed. The low energy absorption appears with a time delay of 5 ps and has its peak at 680 nm (1.8 eV). This band position is coincident with the well known ECS radical ion (polaron) absorption and is therefore assigned to this type of photogenerated charged species. The other two absorptions appear at higher energies. One of them is situated at 2.8 eV which is near to the band edge (2.9 eV). It originates immediately with the exciting pulse and is attributed to a neutral excited state. The other one (2.7 eV) is suggested to be due to an ECS diion (bipolaron).
Excimer laser photochemistry of lithographic systems
Authors: Bendig Jürgen , Mitzner Rolf , Dähne Lars 
Published: March 2011

AbstractLaser photochemical methods are useful in the microchemical field and for microlithographic patterning of integrated circuits. For many reactions a difference in the going on and the result of the reaction is obtained at lamp or at laser initiation, respectively. For the photochemists engaged in lithography the most important properties are: intensity and collimated beam. Several excimer laser exposure systems have been developed in the last years, the importance of which is increasing. At high peak power densities of the excimer laser radiation, new phenomena in photochemical and/or lithographic behaviour are observed. The wavelength‐dependent sensitivity of the positively working naphthoquinone diazide resists is caused by the change of the absorption spectrum within the pulse duration. The intensity‐dependent gradation and resolution of the investigated negatively working azide resists are the result of the further excitation of the intermediately formed nitrenes.
Laserphotochemistry by holographic grating experiments with quantum limited detection sensitivity and holographic optical information storage by photopolymer systems
Authors: Bräuchle Ch. R. 
Published: March 2011

AbstractHolographic methods are most widely known as techniques for producing three dimensional pictures. However, they can also be used to investigate photochemical and photophysical processes of molecules. Holographic gratings produced by cw and pulsed laser sources have been employed successfully in these investigations during the last decade. In this paper a newly developed holographic grating technique, called phasemodulated holography (PMH), is presented. With this technique for the first time a separated and simultaneous monitoring of the amplitude and phase gratings including the absolute signs of these contributions is possible. Thus, hologram formation mechanisms and the underlying photochemistry can be studied in great detail. This feature and an up to eight orders of magnitude improvement of detection sensitivity (quantum limited detection sensitivity) over conventional techniques makes PMH an ideal tool for the investigation of new materials for holographic optical information storage. This will be demonstrated for several examples i.e. photoactive molecules incorporated in polymer systems.
Laser induced polymerization and crosslinking in imaging materials
Authors: Baumann Reinhard , Roth H.‐Klaus , Fritzsche Klaus 
Published: March 2011

AbstractPhotoactive polymer systems for laser direct imaging processes have become of interest in the last years because of their applicability in the fields of plate making and printed circuit board manufacture. In this paper a method shall be presented to study the sensitivity of photopolymer systems and the deviation from the direct proportionality between the intrinsic laser energy and the monomer conversion, in close connection with the conditions of optical recording taking into account the intensity distribution within the laser beam. That is the reciprocity effect of photopolymer systems under laser irradiation. The method will be demonstrated studying (a) unsaturated polyester and (b) multifunctional acrylate based photopolymer systems.
Recent advances in the study of biopolymers
Authors: Katchalski‐Katzir Ephraim 
Published: March 2011

AbstractIn describing some of the macromolecular characteristics of the nucleic acids, particularly DNA, and of representative proteins, the following aspects are discussed: computer‐assisted modeling as a useful tool for depicting the three‐dimensional structures and macromolecular characteristics of biopolymers; conformational flexibility in biopolymers; parameters determining protein recognition; and the importance of the three‐dimensional structure of antibodies, enzymes, receptors, ion channels, and proteins interacting with nucleic acids, in determining their characteristic biological functions. Many of the problems raised by molecular biologists concerning the mode of action of biopolymers could be tackled by polymer chemists, because of their experience in dealing theoretically as well as experimentally with synthetic and native high molecular weight compounds.
Advances in ultra‐high load polymer‐supported peptide synthesis with phenolic supports: 1. A selectively‐labile c‐terminal spacer group for use with a base‐mediated n‐terminal deprotection strategy and fmoc amino acids
Authors: Butwell Francis G.W. , Haws Edmund J. , Epton Roger 
Published: March 2011

AbstractCrosslinked poly(N‐[2‐(4‐hydroxphenyl)ethyl]‐acrylamide) has been modified by conversion of each pendant 4‐hydroxyphenyl group to its 2‐(4‐hydroxymethyl‐phenoxy)ethanoyl‐L‐prolyl ester. This provides a spacer group which makes the polymer matrix suitable for solid (gel) phase peptide synthesis with Fmoc amino acids at ultra‐high load (2.2 mmol g−1 of spacer‐modified support). The selectively labile linkages incorporated in the spacer group provide for peptide detachment by either mild acidolysis or hydrazinolysis. The products of hydrazinolysis of intermediate and final peptide‐matrix assemblies are amenable to analysis by high‐pressure liquid chromatography (HPLC).
Polymers as matrices for whole cell immobilization
Authors: Klein Joachim 
Published: March 2011

AbstractThe immobilization of whole microbial cells has become an important tool in the development of biocatalytic processes in the pharmaceutical and food industry. Not only dead, i.e. non growing cells, but recently with higher priority living and growing cells are the biological species, for which simple and efficient polymeric carriers had to be found. In comparison to other methods, like adsorption or encapsulation, entrapment into a polymer network is the most widely used technique. The network can be formed on the basis of a)ionic interactions (ionotropic gelation of polyelectrolytes), b) of polycondensation reactions (epoxides, polyurethanes, silicones) or c) of polymerization reactions (crosslinking polymerization of vinylic monomers, oligomers or polymers). The characteristic features and the efficiency‐controlling parameters of some immobilized cells systems are discussed as illustrative examples.
Investigation of the carrier function of polypeptides. Synthesis, conformation and cytotoxicity of oxazolone conjugates of poly(Lys) and poly[Lys‐(DL‐ALAm)]
Authors: Hudecz Ferenc , Kajtȧr Judit , Kurucz IstvȧN , Kovȧcs Attila L. , Szekerke MȧRia 
Published: March 2011

AbstractA new group of synthetic macromolecular conjugates was synthesised in which poly(Lys) or a branched polypeptide poly[Lys‐(DL‐Alam)] (m≅3) were used as carrier and 4‐(ethoxymethylene)‐2–phenyl–5 (4H)‐oxazolone as hapten. These conjugates were characterized by amino acid analysis, identification of terminal residues of the side chain, sedimentation analysis. The conformation of conjugates and of carrier polypeptides were analyzed by circular dichroism spectroscopy in water solutions at various pH and ionic strengths. These data indicated a marked dependence of the conformation of the conjugate on the structure of carrier and on the number of the side chain terminal haptens (phOx). In vitro cytotoxicity of these polymers was also investigated using two different assays, by measuring the viability of isolated rat liver cells and the effect on growth of HeLa cells. Toxicity of polypeptides could be diminished by conjugates containing a higher amount of oxazolone. These conjugates with defined conformation and toxicological properties are considered suitable to analyse the carrier function of branched polypeptides, particularly the interaction with the immunological network.
Polymeric supports for affinity chromatography and high‐performance affinity chromatography
Authors: Ernst‐Cabrera Karin , Wilchek Meir 
Published: March 2011

AbstractAffinity chromatography is the most selective chromatographic method for the purification of biologically active materials. It is based on the biospecific interaction of the substrates with a ligand, which is chemically immobilized onto a suitable matrix (support). Different matrices provided by natural and synthetic polymers are used for the preparation of affinity supports. In this communication we describe and compare the properties of various supports based on polysaccharides, polyacrylamides and inorganic materials. In particular, we discuss the utility of different silica derivatives (especially primary hydroxyl silica) for the immobilization of ligands and high‐performance affinity chromatography.