Mixtures of cationic copolymers and oppositely charged surfactants: effect of polymer charge density and ionic strength on the adsorption behavior at the silica-aqueous interface.

This study addresses polymer-surfactant interactions at solid-liquid interfaces and how these can be manipulated by modulating the association between ionic surfactant and oppositely charged polymer, with a particular focus on electrostatic interactions. For this purpose, the interaction of a series of cationic copolymers of vinylpyrrolidone and quaternized vinylimidazol with sodium dodecyl sulfate (SDS) at the silica-aqueous interface was followed by in situ ellipsometry. To reveal the nature of the interaction, we performed measurements for different copolyion charge densities, in the absence and presence of added salt.

Preparation of calcium alginate nanoparticles using water-in-oil (W/O) nanoemulsions.

A procedure for the preparation of calcium alginate nanoparticles in the aqueous phase of water-in-oil (W/O) nanoemulsions was developed. The emulsions were produced from mixtures of the nonionic surfactant tetraethylene glycol monododecyl ether (C(12)E(4)), decane, and aqueous solutions of up to 2 wt % sodium alginate by means of the phase inversion temperature (PIT) emulsification method. This method allows the preparation of finely dispersed emulsions without a large input of mechanical energy.

Ruthenium(II) arene complexes with chelating chloroquine analogue ligands: synthesis, characterization and in vitro antimalarial activity.

Three new ruthenium complexes with bidentate chloroquine analogue ligands, [Ru(η(6)-cym)(L(1))Cl]Cl (1, cym = p-cymene, L(1) = N-(2-((pyridin-2-yl)methylamino)ethyl)-7-chloroquinolin-4-amine), [Ru(η(6)-cym)(L(2))Cl]Cl (2, L(2) = N-(2-((1-methyl-1H-imidazol-2-yl)methylamino)ethyl)-7-chloroquinolin-4-amine) and [Ru(η(6)-cym)(L(3))Cl] (3, L(3) = N-(2-((2-hydroxyphenyl)methylimino)ethyl)-7-chloroquinolin-4-amine) have been synthesized and characterized. In addition, the X-ray crystal structure of 2 is reported. The antimalarial activity of complexes 1-3 and ligands L(1), L(2) and L(3), as well as the compound N-(2-(bis((pyridin-2-yl)methyl)amino)ethyl)-7-chloroquinolin-4-amine (L(4)), against chloroquine sensitive and chloroquine resistant Plasmodium falciparum malaria strains was evaluated.

Challenging packaging limits and infectivity of phage λ.

The terminase motors of bacteriophages have been shown to be among the strongest active machines in the biomolecular world, being able to package several tens of kilobase pairs of viral genome into a capsid within minutes. Yet, these motors are hindered at the end of the packaging process by the progressive buildup of a force-resisting packaging associated with already packaged DNA. In this experimental work, we raise the issue of what sets the upper limit on the length of the genome that can be packaged by the terminase motor of phage λ and still yield infectious virions and the conditions under which this can be efficiently performed.

Salicylamide and salicylglycine oxidovanadium complexes with insulin-mimetic properties.

Reaction of N-(2-hydroxybenzyl)-N-(2-picolyl) glycine (H(2)papy) with VOSO(4) in water gives the oxidovanadium(V) oxido-bridged dimer [{(papy)(VO)}(2) μ-O)] (1). Similarly, reaction of N-(2-hydroxybenzyl) glycine (H(2)glysal) with VOSO(4) gives [(glysal)VO(H(2)O)] (2) and reaction of salicylamide (Hsalam) with VOSO(4) in methanol gives [(salam)(2)VO] (3). The crystal structure of the oxido-bridged complex 1 is reported.

Comments on the separation efficiency of asymmetrical flow field-flow fractionation in channels of constant channel and crossflow velocities leading to constant separation efficiency.

It is shown theoretically that a claim in the literature about the overall separation efficiency of asymmetrical flow FFF channels being improved by geometries that permit a uniform channel flow velocity throughout the channel length is untrue.

The transition from a molecular to a continuum solvent in electrical double layers showing ion-ion correlation effects.

We analyze, using Monte Carlo simulations, how a dielectric medium, modeled as a Stockmayer fluid, modulates the force between two similarly charged surfaces. A major objective is to provide a basis for understanding the strengths and weaknesses of the primitive model. The system studied has uniformly charged walls separated by counterions and solvent, where the latter is kept at constant chemical potential as the separation between the walls is varied.

Kinetic modelling reveals current limitations in the production of ethanol from xylose by recombinant Saccharomyces cerevisiae.

Saccharomyces cerevisiae lacks the ability to ferment the pentose sugar xylose that is the second most abundant sugar in nature. Therefore two different xylose catabolic pathways have been heterologously expressed in S. cerevisiae.

Synthesis, characterization and antimalarial activity of new chromium arene-quinoline half sandwich complexes.

Organometallic analogs of chloroquine (CQ) are of interest as drug candidates that may be able to overcome the widespread chloroquine resistance developed by malaria parasites. Two new chromium arene CQ-analogs: [η(6)-N-(7-chloroquinolin-4-yl)-N'-(2-dimethylamino-methylbenzyl)-ethane-1,2-diamine]tricarbonylchromium 4 and [η(6)-N-(7-chloroquinolin-4-yl)-N'-(2-dimethylaminobenzyl)-ethane-1,2-diamine]tricarbonylchromium 9 have been synthesized and characterized. In addition, X-ray crystal structures of the intermediates (η(6)-benzyldimethylamine)tricarbonylchromium 2, [η(6)-2-((dimethylamino)methyl) benzaldehyde]tricarbonylchromium 3 and p-(η(6)-dimethylaminobenzaldehyde)tricarbonyl chromium 8 are reported.

Isolation of xylose isomerases by sequence- and function-based screening from a soil metagenomic library.

Background: Xylose isomerase (XI) catalyses the isomerisation of xylose to xylulose in bacteria and some fungi. Currently, only a limited number of XI genes have been functionally expressed in Saccharomyces cerevisiae, the microorganism of choice for lignocellulosic ethanol production. The objective of the present study was to search for novel XI genes in the vastly diverse microbial habitat present in soil.

Flavonoids: precipitation kinetics and interaction with surfactant micelles.

Polyphenolic substances, such as flavonoids, attract considerable interest due to their ability to act as antioxidants. The vast majority of studies published deal with the nutritional, biochemical, or chemical structure aspects of these substances while few reports exist on the physico-chemical properties as well as solution behavior of the substances. In this article we report on the precipitation kinetics of naringenin, quercetin, and rutin in pure water as well as in micellar solutions of Tween 80.

Algal MIPs, high diversity and conserved motifs.

Background: Major intrinsic proteins (MIPs) also named aquaporins form channels facilitating the passive transport of water and other small polar molecules across membranes. MIPs are particularly abundant and diverse in terrestrial plants but little is known about their evolutionary history. In an attempt to investigate the origin of the plant MIP subfamilies, genomes of chlorophyte algae, the sister group of charophyte algae and land plants, were searched for MIP encoding genes.

Nanoparticle-based pseudostationary phases in CEC: a breakthrough in protein analysis?

This review focuses on major trends in nanoparticle-based pseudostationary phase (PSP) CEC since the publication of our previous reviews within nanoparticle-based CEC [Nilsson, C., et al., Electrophoresis 2006, 27, 76-83; Nilsson, C.

Synthesis, characterization, and reactivity studies of heterodinuclear complexes modeling active sites in purple acid phospatases.

To model the heterodinuclear active sites in plant purple acid phosphatases, a mononuclear synthon, [Fe(III)(H(2)IPCPMP)(Cl(2))][PF(6)] (1), has been generated in situ from the ligand 2-(N-isopropyl-N-((2-pyridyl)methyl)aminomethyl)-6-(N-(carboxylmethyl)-N-((2-pyridyl)methyl)amino methyl)-4-methylphenol (IPCPMP) and used to synthesize heterodinuclear complexes of the formulas [Fe(III)M(II)(IPCPMP)(OAc)(2)(CH(3)OH)][PF(6)] (M = Zn (2), Co (3), Ni (4), Mn (5)), [Fe(III)Zn(II)(IPCPMP)(mpdp)][PF(6)] (6) (mpdp = meta-phenylene-dipropionate), and [Fe(III)Cu(II)(IPCPMP) (OAc)}(2)(μ-O)][PF(6)] (7). Complexes 2-4, 6, and 7 have been crystallographically characterized. The structure of 6 is a solid state coordination polymer with heterodinuclear monomeric units, and 7 is a tetranuclear complex consisting of two heterodinuclear phenolate-bridged Fe(III)Cu(II) units bridged through a μ-oxido group between the two Fe(III) ions.

Chemo-enzymatic epoxidation-process options for improving biocatalytic productivity.

The reactor choice is crucial when designing a process where inactivation of the biocatalyst is a problem. The main bottleneck for the chemo-enzymatic epoxidation has been found to be enzyme inactivation by the hydrogen peroxide, H(2) O(2) , substrate. In the work reported here, the effect of reaction parameters on the reaction performance have been investigated and used to establish suitable operating strategies to minimize the inactivation of the enzyme, using rapeseed methyl ester (RME) as a substrate in a solvent-free system.

Size separations of starch of different botanical origin studied by asymmetrical-flow field-flow fractionation and multiangle light scattering.

Asymmetrical-flow field-flow fractionation combined with multiangle light scattering and refractive index detection has been revealed to be a powerful tool for starch characterization. It is based on size separation according to the hydrodynamic diameter of the starch components. Starch from a wide range of different botanical sources were studied, including normal starch and high-amylose and high-amylopectin starch.

Malt in combination with Lactobacillus rhamnosus increases concentrations of butyric acid in the distal colon and serum in rats compared with other barley products but decreases viable counts of cecal bifidobacteria.

Several substances, including glutamine and propionic acid but in particular butyric acid, have been proposed to be important for colonic health. β-Glucans lead to the formation of comparatively high amounts of butyric acid, and germinated barley foodstuff obtained from brewer's spent grain (BSG), containing high amounts of β-glucans and glutamine, has been reported to reduce the inflammatory response in the colon of patients with ulcerative colitis. The present study examines how 3 barley products, whole grain barley, malt, and BSG, affect SCFA in the hindgut and serum of rats and whether the addition of Lactobacillus rhamnosus 271 to each of these diets would have further effects.

Antifouling activity of simple synthetic diterpenoids against larvae of the barnacle Balanus albicostatus Pilsbry.

Five new pimarane diterpenoids 1-5 were synthesized using ent-8(14)-pimarene-15R,16-diol as starting material. The structures were elucidated by means of extensive NMR and MS analysis. The antifouling activity against larval settlement of the barnacle Balanus albicostatus were evaluated using capsaicin as a positive control.

Simulations of high-dielectric Stockmayer fluids in hyperspherical geometry.

The static dielectric properties of Stockmayer fluids are investigated in the hyperspherical geometry, S(3). Different methods of obtaining the static dielectric constant ε(r) are compared. Tested methods include the evaluation of the Kirkwood factor, fluctuations of the total dipole moment, and a two-center potential correlation formula to obtain the dielectric constant through effective interactions.

Computational modeling of the mechanism of urease.

In order to elucidate aspects of the mechanism of the hydrolytic enzyme urease, theoretical calculations were undertaken on a model of the active site, using density functional theory. The bridging oxygen donor that has been found in the crystal structures was determined to be a hydroxide ion. The initial coordination of urea at the active site occurs most likely through the urea oxygen to the nickel ion with the lowest coordination number.

Proton and cation transport activity of the M2 proton channel from influenza A virus.

The M2 protein is a small, single-span transmembrane (TM) protein from the influenza A virus. This virus enters cells via endosomes; as the endosomes mature and become more acidic M2 facilitates proton transport into the viral interior, thereby disrupting matrix protein/RNA interactions required for infectivity. A mystery has been how protons can accumulate in the viral interior without developing a large electrical potential that impedes further inward proton translocation.

Unsymmetrical dizinc complexes as models for the active sites of phosphohydrolases.

The unsymmetrical dinucleating ligand 2-(N-isopropyl-N-((2-pyridyl)methyl)aminomethyl)-6-(N-(carboxylmethyl)-N-((2-pyridyl)methyl)aminomethyl)-4-methylphenol (IPCPMP or L) has been synthesized to model the active site environment of dinuclear metallohydrolases. It has been isolated as the hexafluorophosphate salt H(4)IPCPMP(PF(6))(2) x 2 H(2)O (H(4)L), which has been structurally characterized, and has been used to form two different Zn(II) complexes, [{Zn(2)(IPCPMP)(OAc)}(2)][PF(6)](2) (2) and [{Zn(2)(IPCPMP)(Piv)}(2)][PF(6)](2) (3) (OAc = acetate; Piv = pivalate). The crystal structures of and show that they consist of tetranuclear complexes with very similar structures.

Structural, functional and chemical changes in Pseudozyma antarctica lipase B on exposure to hydrogen peroxide.

The effect on primary, secondary, tertiary and quaternary structure of Pseudozyma (formerly Candida) antarctica lipase B (PalB) on exposure to hydrogen peroxide was investigated using nano-electrospray ionization-mass spectrometry (nano-ESI-MS), liquid chromatography tandem mass spectrometry (LC/MS/MS), circular dichroism (CD), and dynamic light scattering (DLS). Treatment with hydrogen peroxide generated heavier protein variants, with a mass gain that increased with increasing incubation time. Furthermore, elevated concentration of H(2)O(2) was shown to result in partial fragmentation of the protein.

Higher plant calreticulins have acquired specialized functions in Arabidopsis.

Background: Calreticulin (CRT) is a ubiquitous ER protein involved in multiple cellular processes in animals, such as protein folding and calcium homeostasis. Like in animals, plants have evolved divergent CRTs, but their physiological functions are less understood. Arabidopsis contains three CRT proteins, where the two CRTs AtCRT1a and CRT1b represent one subgroup, and AtCRT3 a divergent member.

Characterization of the properties of Pediococcus parvulus for probiotic or protective culture use.

Pediococcus parvulus 2.6 (previously Pediococcus damnosus 2.6, here confirmed as P.