Polymer Subunit Research Articles

PEG-functionalized carbazole-based polymers for UV-protected hydrophilic glass coatings

The UV-absorbing and non-fogging glass coatings containing carbazole-based conjugated backbone with different lengths of hydrophilic PEG subunit (KP-PEG) were produced. The characterizations of the polymers were carried out by using different techniques such as FT-IR, 1H NMR, GPC, TGA and DSC. Transmittance and thin-film morphology analyses, which are essential for UV protection and wettability, were investigated by UV–Vis absorption, AFM and TEM techniques, respectively. Transparent thin films prepared by the polymer solutions in chloroform were obtained by spin coating method at a scan rate of 2000 rpm. The wettability performance and antifogging properties of these surfaces were investigated depending on the PEG length in the polymer subunit. The water contact angle of the surfaces was improved to the range between 60° and 29° depending on the amount of PEG group. KP-PEG750 is the best polymer thin film in terms of having the highest roughness, optimum UV absorption and the low contact angle value.

The Non-solventogenic Clostridium beijerinckii Br21 Produces 1,3-Propanediol From Glycerol With Butyrate as the Main By-Product

Ever-increasing biofuel production has raised the supply of glycerol, an abundant waste from ethanolic fermentation and transesterification, for biodiesel production. Glycerol can be a starting material for sustainable production of 1,3-propanediol (1,3 PD), a valued polymer subunit. Here, we compare how Clostridium pasteurianum DSMZ 525, a well-known 1,3-PD-producer, and the non-solventogenic Clostridium beijerinckii Br21 perform during glycerol fermentation. Fermentative assays in 80-, 390-, or 1,100-mM glycerol revealed higher 1,3-PD productivity by DSMZ 525 compared to Br21. The highest 1,3-PD productivities by DSMZ 525 and Br21 were obtained in 390 mM glycerol: 3.01 and 1.70 mM h−1, respectively. Glycerol uptake by the microorganisms differed significantly: C. beijerinckii Br21 consumed 41.1, 22.3, and 16.3%, while C. pasteurianum consumed 93, 44.5, and 14% of the initial glycerol concentration in 80, 390, and 1,100 mM glycerol, respectively. In 1,100 mM glycerol, C. beijerinckii Br21 growth was delayed. Besides 1,3-PD, we detected butyrate and acetate during glycerol fermentation by both strains. However, at 80 mM glycerol, C. beijerinckii Br21 formed only butyrate as the by-product, which could help downstream processing of the 1,3-PD fermentation broth. Therefore, C. beijerinckii Br21, an unexplored biocatalyst so far, can be used to convert glycerol to 1,3-PD and can be applied in biofuel biorefineries.

Effect of interaction between sorbitol and gelatin on gelatin properties and its mechanism under different citric acid concentrations

In this study, the effects of citric acid (CA) concentrations on the gelatin/sorbitol gel properties and the interaction mechanisms were investigated. Furthermore, the alternative effect of sorbitol on sucrose was also investigated and compared in gelatin gel systems. The results showed that the gel strength, viscosity and gelling/melting temperatures of gelatin could be “protected” due to the sorbitol addition at a low CA concentration (<0.5%). As the CA concentration gradually increased, the values of these indicators in the gelatin/sorbitol group were close to those of the gelatin/sucrose group, showing no obvious difference. The SDS-PAGE results indicated that this “protective” effect of sorbitol on gelatin was mainly reflected in the reduction of polymer subunit components degradation of gelatin. The X-ray diffraction (XRD) results showed that the sorbitol addition promoted the triple helical structure formation of gelatin at a low CA concentration (<0.5%). However, the high CA concentration not only destroyed the hydrogen bonds formed by sorbitol, but also destroyed the structure of the gelatin. The increase in the yellowness value of the gel color and the peak shifts of the amide I and II bands probably implied the occurrence of the Maillard reactions between sucrose and gelatin, which is not found in gelatin/sorbitol group. Hence, sorbitol can be used as a good alternative to sucrose in gelatin sweet products.

Microbial biosynthesis and in vivo depolymerization of intracellular medium-chain-length poly-3-hydroxyalkanoates as potential route to platform chemicals.

Biosynthesis and in vivo depolymerization of intracellular medium-chain-length poly-3-hydroxyalkanoates (mcl-PHA) in Pseudomonas putida Bet001 grown on lauric acid were studied. Highest mcl-PHA fraction (>50 % of total biomass) and cell concentration (8gL-1 ) were obtained at carbon-to-nitrogen (C/N) ratio 20, starting cell concentration 1gL-1 , and 48H fermentation. The mcl-PHA comprised of 3-hydroxyhexanoate (C6 ), 3-hydroxyoctanote (C8 ), 3-hydroxydecanoate (C10 ), and 3-hydroxydodecanoate (C12 ) monomers. In vivo action was studied in a mineral liquid medium without carbon source, and in different buffer solutions with varied pH, molarity, ionic strength, and temperature. The monomer liberation rate reflected the mol percentage distribution of the initial polymer subunit composition. Rate and percentage of in vivo depolymerization were highest in 0.2M Tris-HCl buffer (pH 9, strength=0.2M, 30°C) at 0.21gL-1 H-1 and 98.6±1.3 wt%, respectively. There is a congruity vis-à-vis to specific buffer type, molarity, pH, ionic strength, and temperature values for superior in vivo depolymerization activities. Direct products from in vivo depolymerization matched the individual monomeric composition of native mcl-PHA. It points to exo-type reaction for the in vivo process, and potential biological route to chiral molecules.

In vivo and in vitro depolymerizations of intracellular medium-chain-length poly-3-hydroxyalkanoates produced by Pseudomonas putida Bet001

ABSTRACTIn vivo and in vitro depolymerizations of intracellular medium-chain-length poly-3-hydroxyalkanoates (mcl-PHA) in Pseudomonas putida Bet001 grown on lauric acid was studied. Both processes were studied under optimum conditions for mcl-PHA depolymerization viz. 0.2 M Tris-HCl buffer, pH 9, ionic strength (I) = 0.2 M at 30°C. For in vitro depolymerization studies, cell-free system was obtained from lysing bacterial cells suspension by ultrasonication at optimum conditions (frequency 37 kHz, 30% of power output, <25°C for 120 min). The comparison between in vivo and in vitro depolymerizations of intracellular mcl-PHA was made. In vitro depolymerization showed lower depolymerization rate but higher yield compared to in vivo depolymerization. The monomer liberation rate reflected the mol% distribution of the initial polymer subunit composition, and the resulting direct individual products of depolymerization were identical for both in vivo and in vitro processes. It points to exo-type reaction for both processes, and potential biological route to chiral molecules.

Comparative Assessment of Reactogenicity and Immunogenicity of Commercial Influenza Inactivated Vaccines: Polymer-Subunit Grippol plus, Subunit Influvac, Split Vaccine Waxigrip

Objective. To compare the reactogenicity and immunogenicity of inactivated influenza vaccines: Grippol Plus polymer subunit vaccine, Influvac subunit vaccine, and Vaxigrip split vaccine as part of influenza prevention in people aged 18 - 55 with no pre-existing conditions. Materials and methods. Comparative study of three groups of volunteers with no pre-existing conditions using coded serum samples. Randomisation: 1:1:1. Group 1:100 people vaccinated with Grippol® Plus, Group 2:100 people vaccinated with Influvac, Group 3: 100 people vaccinated with Vaxigrip. The study looked into the levels of specific hemagglutination-inhibition antibodies to influenza viruses in a standard hemagglutination inhibition assay (HAI), with the coding of sera obtained before the vaccination and 28 days post-vaccination. The seroconversion rate (share of patients with the antibody titer increase of more than 4x) and seroprotection rate (share of patients with antibody titer &gt; 1:40) were measured. Reactogenicity was evaluated based on the intensity of systemic and local reactions during the first five days post-vaccination. Results. Reactogenicity: in general the number and intensity of systemic and local reactions in all the groups was insignificant, the reactions were mild and required no treatment with medications. Tolerability levels were high. There was a reliable decline in local reactions to subunit vaccines over time. Immunogenicity: the seroprotection rate for the A/H1N1 strain on day 28 post-vaccination was 95.0% for the Grippol Plus group, 95.0% for the Influvac group, and 96.0% for the Vaxigrip group. The seroprotection rate for the A/H3N2 strain on day 28 post-vaccination was 90.9% for the Grippol Plus group, 90.0% for the Influvac group, and 96.0% for the Vaxigrip group. The seroprotection rate for the B strain on day 28 post-vaccination was 99.0% for the Grippol Plus group, 100.0% for the Influvac group, and 100.0% for the Vaxigrip group. Conclusion: the study found that the Grippol Plus, Influvac, and Vaxigrip vaccines have similar efficacy in vaccination against the A/H1N1, A/H3N2, and В strains 28 days post-vaccination. All the vaccines tested were in line with the CPMP requirements to the immunogenicity of human influenza vaccines. All the vaccines had a similar safety profile, but the incidence of injection site pain, swelling and itching was reliably lower in those vaccinated with the Grippol Plus and Influvac vaccines as compared to the Vaxigrip vaccine.

Exploring hemostatic and thrombolytic potential of heynein - A cysteine protease from Ervatamia heyneana latex

Ethnopharmacological relevanceThe latex of Ervatamia heyneana (Wall.) T. Cooke plant has been used for wound healing and various skin diseases by Indian tribes and folklore. Aim of the studyTo validate the scientific basis of heynein – a key protease of Ervatamia heyneana, in hemostasis and wound healing process. Materials and methodsThe latex from E. heyneana was processed and subjected to two step purification. The purified heynein was assayed for proteolytic activity using casein as substrate and also attested by zymography. The inhibition studies confirmed the nature of heynein. Pure fibrinogen was used for fibrinogenolytic activity and citrated plasma was used for coagulant and fibrinolytic activities. The edema inducing action and hemorrhagic activity of heynein were assessed on mice model. ResultsThe purified heynein exhibited proteolytic activity, which was confirmed by caseinolytic assay and zymography. The inhibition studies confirmed heynein to be a cysteine protease. Heynein showed complete hydrolysis of all the three subunits of human fibrinogen (Aα, Bβ, γ). It exhibited strong pro-coagulant activity by reducing plasma clotting time from 248 to 39s at 40µg concentration. Heynein cleaved α polymer subunit in fibrin clot and did not induce edema and hemorrhage in mice models. The non-hemorrhagic nature was supported with histopathological studies of skin samples. ConclusionHeynein displays strong pro-coagulant action associated with fibrin(ogen)olytic activity. This provides basis for the observed pharmacological action of Ervatamia heyneana and thereby justifies its use in folk medicine.

Specific and Nonspecific Immunoprophilaxis of Respiratory Infections and Flu in Children with Allergic Diseases

Relevance. The only way to reduce the incidence of vaccination-controlled infections and to prevent epidemics at the current stage is a 95% preventive vaccination coverage. It means that not only healthy children are subject to vaccination, but also children with various diseases. Object: to justify the need of specific and nonspecific immunoprophilaxis of respiratory infections and flu for children with allergic diseases. Patients and methods. Comparative analysis of domestic and foreign-made polymer subunit vaccine tolerance was conducted among 335 children aged 3–17 years with various allergic diseases. The research was conducted during three seasons of epidemics — 2011–2014 years. The subjects of analysis were vaccination tolerance, course of the underlying disease and the frequency of acute respiratory infections within one year after immunization. Specific immune response was assessed 1 and 6 months after vaccination. Results . The lower quantity and severity of weak local and general reactions was observed in all groups of children (both healthy and with allergic diseases) immunized by the domestic vaccine. No significant differences in immunogenicity of domestic and foreign-made influenza vaccines were detected. Furthermore, the level of postvaccination immunity remains high after immunization of patients with both bronchial asthma and atopic dermatitis. No cases of exacerbation of chronic disease associated with influenza vaccination are detected. Reduction of bronchial asthma frequency was associated with a reduction of acute respiratory infections frequency. Conclusion . Vaccination of healthy children and children with bronchial asthma and atopic dermatitis is an essential and secure measure that increases the efficiency of patients with current treatment of various allergic diseases and decreases the frequency of flu and acute respiratory infections.

The Kil peptide of bacteriophage λ blocks Escherichia coli cytokinesis via ZipA-dependent inhibition of FtsZ assembly.

Assembly of the essential, tubulin-like FtsZ protein into a ring-shaped structure at the nascent division site determines the timing and position of cytokinesis in most bacteria and serves as a scaffold for recruitment of the cell division machinery. Here we report that expression of bacteriophage λ kil, either from a resident phage or from a plasmid, induces filamentation of Escherichia coli cells by rapid inhibition of FtsZ ring formation. Mutant alleles of ftsZ resistant to the Kil protein map to the FtsZ polymer subunit interface, stabilize FtsZ ring assembly, and confer increased resistance to endogenous FtsZ inhibitors, consistent with Kil inhibiting FtsZ assembly. Cells with the normally essential cell division gene zipA deleted (in a modified background) display normal FtsZ rings after kil expression, suggesting that ZipA is required for Kil-mediated inhibition of FtsZ rings in vivo. In support of this model, point mutations in the C-terminal FtsZ-interaction domain of ZipA abrogate Kil activity without discernibly altering FtsZ-ZipA interactions. An affinity-tagged-Kil derivative interacts with both FtsZ and ZipA, and inhibits sedimentation of FtsZ filament bundles in vitro. Together, these data inspire a model in which Kil interacts with FtsZ and ZipA in the cell to prevent FtsZ assembly into a coherent, division-competent ring structure. Phage growth assays show that kil+ phage lyse ∼30% later than kil mutant phage, suggesting that Kil delays lysis, perhaps via its interaction with FtsZ and ZipA.

A formalism for scattering of complex composite structures. I. Applications to branched structures of asymmetric sub-units

We present a formalism for the scattering of an arbitrary linear or acyclic branched structure build by joining mutually non-interacting arbitrary functional sub-units. The formalism consists of three equations expressing the structural scattering in terms of three equations expressing the sub-unit scattering. The structural scattering expressions allow composite structures to be used as sub-units within the formalism itself. This allows the scattering expressions for complex hierarchical structures to be derived with great ease. The formalism is generic in the sense that the scattering due to structural connectivity is completely decoupled from internal structure of the sub-units. This allows sub-units to be replaced by more complex structures. We illustrate the physical interpretation of the formalism diagrammatically. By applying a self-consistency requirement, we derive the pair distributions of an ideal flexible polymer sub-unit. We illustrate the formalism by deriving generic scattering expressions for branched structures such as stars, pom-poms, bottle-brushes, and dendrimers build out of asymmetric two-functional sub-units.

Monomeric, oligomeric, and polymeric flavan-3-ol composition of wines and grapes from Vitis vinifera L. Cv. Graciano, Tempranillo, and Cabernet Sauvignon.

The monomeric, oligomeric, and polymeric flavan-3-ol composition of wines, grape seeds, and skins from Vitis vinifera L. cv. Graciano, Tempranillo, and Cabernet Sauvignon has been studied using (1) fractionation by polyamide column chromatography followed by HPLC/ESI-MS analysis, (2) fractionation on C(18) Sep-Pak cartridges followed by reaction with vanillin and acid-catalyzed degradation in the presence of toluene-alpha-thiol (thiolysis). The content of monomers ((+)-catechin and (-)-epicatechin), procyanidin dimers (B3, B1, B4, and B2), trimers (T2 and C1), and dimer gallates (B2-3-O-gallate, B2-3'-O-gallate, and B1-3-O-gallate) ranged from 76.93 to 133.18 mg/L in wines, from 2.30 to 8.21 mg/g in grape seeds, and from 0.14 to 0.38 mg/g in grape skins. In wines, the polymeric fraction represented 77-84% of total flavan-3-ols and showed a mean degree of polymerization (mDP) value of 6.3-13.0. In grapes, the polymeric fraction represented 75-81% of total flavan-3-ols in seeds and 94-98% in skins and showed mDP values of 6.4-7.3 in seeds and 33.8-85.7 in skins. All the monomeric flavan-3-ols and oligomeric procyanidins found in wines were also present in seeds, although differences in their relative abundances were seen. The skin polymeric proanthocyanidins participated in the equilibration of the wine polymeric proanthocyanidin fraction, especially contributing to the polymer subunit composition and mDP.

Role of the DNase-I-Binding Loop in Dynamic Properties of Actin Filament

Effects of proteolytic modifications of the DNase-I-binding loop (residues 39–51) in subdomain 2 of actin on F-actin dynamics were investigated by measuring the rates of the polymer subunit exchange with the monomer pool at steady state and of ATP hydrolysis associated with it, and by determination of relative rate constants for monomer addition to and dissociation from the polymer ends. Cleavage of actin between Gly-42 and Val-43 by protease ECP32 resulted in enhancement of the turnover rate of polymer subunits by an order of magnitude or more, in contrast to less than a threefold increase produced by subtilisin cleavage between Met-47 and Gly-48. Probing the structure of the modified actins by limited digestion with trypsin revealed a correlation between the increased F-actin dynamics and a change in the conformation of subdomain 2, indicating a more open state of the filament subunits relative to intact F-actin. The cleavage with trypsin and steady-state ATPase were cooperatively inhibited by phalloidin, with half-maximal effects at phalloidin to actin molar ratio of 1:8 and full inhibition at a 1:1 ratio. The results support F-actin models in which only the N-terminal segment of loop 39–51 is involved in monomer-monomer contacts, and suggest a possibility of regulation of actin dynamics in the cell through allosteric effects on this segment of the actin polypeptide chain.

Cross-linked dimers with nucleating activity in actin prepared from muscle acetone powder.

A covalently linked actin dimer is identified in solutions of actin prepared from an acetone powder from skeletal muscle. This actin dimer acts as an actin nucleating factor (ANF), decreasing the half-time for spontaneous actin polymerization. ANF reacts with antibodies to both the N- and C-terminal portions of actin on Western blots and migrates during reduced polyacrylamide gel electrophoresis like actin cross-linked with N, N'-p-phenylenebismaleimide. The origin of the cross-linked dimer appears to be related to the presence of carbonyl groups in purified actin. A large number of carbonyls (approximately 0.3/actin) are introduced into actin during the prolonged treatment with acetone in the preparation of the muscle acetone powder from which actin is extracted. Actin extracted from acetone powder prepared by a single acetone wash and actin prepared from bovine spleen, which is not washed with acetone, both contain fewer carbonyl groups (approximately 0.05 carbonyl/actin). ANF forms spontaneously in solutions of polymer actin containing 0.3 carbonyl/actin. We speculate that a reaction between a carbonyl on one actin polymer subunit and a lysine on a neighboring subunit is responsible for ANF formation. The presence of cross-linked actin dimers in commonly used skeletal muscle actin preparations could certainly affect studies of actin polymerization and, particularly, studies of the nucleation reaction. The physiological relevance of ANF is not clear, but given the large cellular concentration of actin, similar reactions yielding ANF could occur in vivo when increased levels of reactive oxygen species are present.

Attenuated total reflection FT–IR study of hydrogen bonding in water/ether mixtures

A FTIR–ATR study of hydrogen bonding in binary aqueous mixtures containing tetrahydrofuran, 1,4-dioxane or poly(ethylene oxide) is reported. Observed spectra were converted to linear absorption coefficient spectra using the Bertie–Eysel procedure. The frequency of the OH stretching mode in isotopically dilute HOD was found to increase with ether concentration, implying a continuous reduction in average hydrogen-bond strength. In water-rich mixtures, the initial gradients were proportional to the number of oxygen atoms in the cyclic ether molecules or in the polymer subunit.

Phase Equilibria in Mixtures of Thermotropic Small Molecular Liquid Crystals and Flexible Polymers

Lebwohl-Lasher nematogenic model and Flory-Huggins theory of mixtures have been combined to describe the phase equilibria in mixtures of thermotropic small molecular liquid crystals and flexible polymers. Monte Carlo simulations on the same model have also been carried out in order to confirm the theoretical predictions. A comparison between theory and Monte Carlo simulation gives very good agreement. The findings include a widening of the nematic (N)/isotropic (I) two phase region with increasing polymer chain length and the isotropic force between polymer subunit and nematogen, exclusion of the polymer coils from the nematic phase and the appearance of an I/I biphasic region when the isotropic interaction exceeds the critical Flory–Huggins interaction parameter χc. A comparison with a real experimental system is also made and the agreement is quite good considering the simplicity of the theoretical model. A discrepancy between theory and experiment is imputed to the existence of an anisotropic interaction between polymer subunit and nematogen according to the existing 2H NMR results, which has not been taken into account in the present stage of theoretical approach. All of these findings are in accord with the present model and lend support to the general validity of Flory–Huggins treatment of mixtures and the Lebwohl–Lasher model for the thermotropic nematic behavior.

The relative contributions of polymer annealing and subunit exchange to microtubule dynamics in vitro.

Microtubules that are free of microtubule-associated protein undergo dynamic changes at steady state, becoming longer but fewer in number with time through a process which was previously assumed to be based entirely on mechanisms of subunit exchange at polymer ends. However, we recently demonstrated that brain and erythrocyte microtubules are capable of joining end-to-end and suggested that polymer annealing may also affect the dynamic behavior of microtubules in vitro (Rothwell, S. W., W. A. Grasser, and D. B. Murphy, 1986, J. Cell Biol. 102:619-627). In the present study, we first show that annealing is a general property of cytoplasmic microtubules and is not a specialized characteristic of erythrocyte microtubules by documenting annealing between tryosinolated and detyrosinolated brain microtubules. We then examine the contributions of polymer annealing and subunit exchange to microtubule dynamics by analyzing the composition and length of individual polymers in a mixture of brain and erythrocyte microtubules by immunoelectron microscopy. In concentrated preparations of short-length microtubules at polymer-mass steady state, annealing was observed to be the principal factor responsible for the increase in polymer length, whereas annealing and subunit exchange contributed about equally to the reduction in microtubule number.

Model of anaphase chromosome movement based on polymer-guided diffusion.

We propose a motility mechanism that may result in the displacement of objects within the cell. The mechanism, which we call polymer-guided diffusion, involves a microscopic cycle of polymer association and dissociation from a lateral binding site. Reassociation occurs at the polymer subunit adjacent to that which has just dissociated, thus generating an apparent sliding movement. The displacement involves only free diffusion and the spontaneous fluctuations of the polymer; the movement thus requires no other energy sources than thermal energy and the energy originally required for the formation of the polymer. In this manner polymer-associated organelles can be guided (inevitably) by diffusional processes toward a final destination. The specific example of the anaphase movement of chromosomes poleward is detailed.

Pyrolysis field desorption mass spectrometry of polymers. III. Aliphatic polyamides

AbstractPyrolysis field desorption mass spectrometry has been performed from various polyamides such as nylon 6, 8, 12, and nylon 66. The pyrolytic behaviour of these compounds depends strongly on the solvent and the temperature program employed. Using formic acid as solvent strong thermal fragmentation is observed, while with 1,1,1,3,3,3‐hexafluoro‐2‐propanol almost exclusively molecular ions or cationized molecules of the monomer building block M are produced. With increasing temperature larger clusters of polymeric subunits (Mn + Na)+ are generated, but thermal fragmentation on the emitter surface also increases. The cationized molecules dominate all spectra. They are found from M3 to M5 or M15 depending on the chain length of the polymer subunit. With increasing temperature, the base peak of the spectrum is shifted to the higher mass end and small signals up to m/z 2000 and above are recorded. Thermal products are mainly formed by water elimination (−18 mu), loss of the acid amide group (−44 mu) after rearrangement and from longer polyamides by loss of the methylene groups (− 42 or 56 mu) by cis‐elimination.These thermal fragmentations of the polymeric substances on the emitter surface can be controlled by appropriate emitter heating and correlate directly with the common chemical knowledge of these materials in the liquid or solid phase. Together with the options of integrating recording, high mass resolution and direct isotope determination, the combination of pyrolysis and field desorption mass spectrometry offers a unique tool for characterization of building blocks and high mass sequences in synthetic polymers.

Hemoglobin binding by isolated polymeric proteins from human haptoglobin types 2-1 and 2-2 Some suggested polymer subunit compositions

1. 1. Some of the individual members of the polymeric series of proteins from human haptoglobin types 2-1 and 2-2 were isolated by gel electrophoresis. By reacting this purified material with less than an equivalent amount of hemoglobin and analyzing the result by electrophoresis, the number of haptoglobin-hemoglobin complexes could be clearly counted. For the haptoglobin 2-1 series, the number of complexes formed was n+1, where n is the serial order, in decreasing electrophoretic mobility, of the haptoglobin polymeric form used. For the haptoglobin 2-2 series, the number of complexes was n+2. 2. 2. For the first three members of haptoglobin 2-1 series, the haptoglobin-hemoglobin composition of the complexes was estimated from scans of the unstained gels. The data indicated that this series consists of 2, 3, 4… αβ haptoglobin subunits, each of which can combine with an αβ subunit of hemoglobin.