Combination of 3--Levulinoyl and 6--Trifluorobenzoyl Groups Ensures α-Selectivity in Glucosylations: Synthesis of the Oligosaccharides Related to α-(1 → 3)-d-Glucan.

Stereospecific α-glucosylation of primary and secondary OH-group at carbohydrate acceptors is achieved using glucosyl -phenyl-trifluoroacetimidate (PTFAI) donor protected with an electron-withdrawing 2,4,5-trifluorobenzoyl (TFB) group at O-6 and the participating levulinoyl (Lev) group at O-3. New factors have been revealed that might explain α-stereoselectivity in the case of TFB and pentafluorobenzoyl (PFB) groups at O-6. They are of conformational nature and confirmed by DFT calculations.

Proteolysis of Micellar β-Casein by Trypsin: Secondary Structure Characterization and Kinetic Modeling at Different Enzyme Concentrations.

Tryptic proteolysis of protein micelles was studied using β-casein (β-CN) as an example. Hydrolysis of specific peptide bonds in β-CN leads to the degradation and rearrangement of the original micelles and the formation of new nanoparticles from their fragments. Samples of these nanoparticles dried on a mica surface were characterized by atomic force microscopy (AFM) when the proteolytic reaction had been stopped by tryptic inhibitor or by heating.

Microlens-assisted microscopy for biology and medicine.

The addition of dielectric transparent microlens in the optical scheme is an effective and at the same time simple and inexpensive way to increase the resolution of a light microscope. For these purposes, spherical and cylindrical microlenses with a diameter of 1-100 μm are usually used. The microlens focuses the light into a narrow beam called a photonic nanojet.

Evaluation of Antibacterial and Antifungal Properties of Low Molecular Weight Chitosan Extracted from Relative to Crab Chitosan.

This study shows the research on the depolymerisation of insect and crab chitosans using novel enzymes. Enzyme preparations containing recombinant chitinase Chi 418 from , chitinase Chi 403, and chitosanase Chi 402 from , all belonging to the family GH18 of glycosyl hydrolases, were used to depolymerise a biopolymer, resulting in a range of chitosans with average molecular weights (M) of 6-21 kDa. The depolymerised chitosans obtained from crustaceans and insects were studied, and their antibacterial and antifungal properties were evaluated.

Expression and Refolding of the Plant Chitinase From for Applications as a Sustainable and Integrated Pest Management.

Recently, the study of chitinases has become an important target of numerous research projects due to their potential for applications, such as biocontrol pest agents. Plant chitinases from carnivorous plants of the genus are most aggressive against a wide range of phytopathogens. However, low solubility or insolubility of the target protein hampered application of chitinases as biofungicides.

A previously unknown way of heme detoxification in the digestive tract of cats.

Free heme is a highly toxic molecule for a living organism and its detoxification is a very important process, especially for carnivorous animals. Here we report the discovery of a previously unknown process for neutralizing free heme in the digestive tract of domestic cats. The cornerstone of this process is the encapsulation of heme into carbonated hydroxyapatite nanoparticles, followed by their excretion with faeces.

Bioconversion of Renewable Plant Biomass. Second-Generation Biofuels: Raw Materials, Biomass Pretreatment, Enzymes, Processes, and Cost Analysis.

The review discusses various aspects of renewable plant biomass conversion and production of the second-generation biofuels, including the types of plant biomass, its composition and reaction ability in the enzymatic hydrolysis, and various pretreatment methods for increasing the biomass reactivity. Conversion of plant biomass into sugars requires the use of a complex of enzymes, the composition of which should be adapted to the biomass type and the pretreatment method. The efficiency of enzymatic hydrolysis can be increased by optimizing the composition of the enzymatic complex and by increasing the catalytic activity and operational stability of its constituent enzymes.

Designing enzyme cocktails from Penicillium and Aspergillus species for the enhanced saccharification of agro-industrial wastes.

The aim of this study was to develop optimized enzyme cocktails, containing native and recombinant purified enzymes from five fungal species, for the saccharification of alkali- and acid-pretreated sugarcane bagasse (SCB), soybean hulls (SBH) and oil palm empty fruit bunches (EFB). Basic cellulases were represented by cellobiohydrolase I (CBH) and endo-glucanase II (EG) from Penicillium verruculosum and β-glucosidase (BG) from Aspergillus niger. Auxiliary enzymes were represented by endo-xylanase A (Xyl), pectin lyase (PNL) and arabinoxylanhydrolase (AXH) from Penicillium canescens, β-xylosidase (BX) from Aspergillus japonicus, endo-arabinase (ABN) from A.

Molecular dynamics simulations of two GH74 endo-processive xyloglucanases and the mutated variants to understand better the mechanism of the enzyme action.

Background: GH74 xyloglucanases are composed of two separate domains connected by two unstructured peptides. Previously, a hypothesis was made that the movement of domains may affect the enzyme mechanism of catalysis.

Methods: The molecular dynamics (MD) simulations of endo-processive xyloglucanases from Paenibacillus odorifer (PoGH74) and Myceliophthora thermophila (MtXeg74A) were carried out.

Effective Zearalenone Degradation in Model Solutions and Infected Wheat Grain Using a Novel Heterologous Lactonohydrolase Secreted by Recombinant .

This paper reports the first results on obtaining an enzyme preparation that might be promising for the simultaneous decontamination of plant feeds contaminated with a polyketide fusariotoxin, zearalenone (ZEN), and enhancing the availability of their nutritional components. A novel ZEN-specific lactonohydrolase (ZHD) was expressed in a strain PCA-10 that was developed previously as a producer of different hydrolytic enzymes for feed biorefinery. The recombinant ZHD secreted by transformed fungal clones into culture liquid was shown to remove the toxin from model solutions, and was able to decontaminate wheat grain artificially infected with a zearalenone-producing .

Lipophilic Metabolites from Five-Needle Pines, Pinus armandii and Pinus kwangtungensis, Exhibiting Antibacterial Activity.

Lipophilic extractive metabolites from needles and defoliated twigs of Pinus armandii and P. kwangtungensis were studied by GC/MS. Needles of P.

From Specific γ-CD/[Nb Cl (H O) ] Recognition to Biological Activity Tuning.

Specific molecular recognition of γ-cyclodextrin (γ-CD) by the cationic hexanuclear niobium [Nb Cl (H O) ] cluster complex in aqueous solutions results in a 1:1 supramolecular assembly {[Nb Cl (H O) ]@γ-CD} . NMR spectroscopy, isothermal titration calorimetry (ITC), and ESI-MS were used to study the interaction between the inorganic cluster and the organic macrocycle. Such molecular association affects the biological activity of [Nb Cl (H O) ] , decreasing its cytotoxicity despite enhanced cellular uptake.

Genotoxic activity of 1,2,3-triazolyl modified furocoumarins and 2,3-dihydrofurocoumarins.

The furocoumarin backbone is a promising platform for chemical modifications aimed at creating new pharmaceutical agents. However, the high level of biological activity of furocoumarins is associated with a number of negative effects. For example, some of the naturally occurring ones and their derivatives can show genotoxic and mutagenic properties as a result of their forming crosslinks with DNA molecules.

Virus-Like Particle Facilitated Deposition of Hydroxyapatite Bone Mineral on Nanocellulose after Exposure to Phosphate and Calcium Precursors.

We produced and isolated tobacco mosaic virus-like particles (TMV VLPs) from bacteria, which are devoid of infectious genomes, and found that they have a net negative charge and can bind calcium ions. Moreover, we showed that the TMV VLPs could associate strongly with nanocellulose slurry after a simple mixing step. We sequentially exposed nanocellulose alone or slurries mixed with the TMV VLPs to calcium and phosphate salts and utilized physicochemical approaches to demonstrate that bone mineral (hydroxyapatite) was deposited only in nanocellulose mixed with the TMV VLPs.

Fluorescent labeling of ursolic acid with FITC for investigation of its cytotoxic activity using confocal microscopy.

Fluorescent labeling is a widely-used approach in the study of intracellular processes. This method is becoming increasingly popular for studying small bioactive molecules of natural origin; it allows us to estimate the vital intracellular changes which occur under their influence. We propose a new approach for visualization of the intracellular distribution of triterpene acids, based on fluorescent labeling by fluoresceine isothiocyanate.

Enzymatic hydrolysis of cellulosic materials using synthetic mixtures of purified cellulases bioengineered at -glycosylation sites.

Mutant forms of recombinant endoglucanase II (EG II, N194A), cellobiohydrolase I (CBH I, N45A) and cellobiohydrolase II (CBH II, N219A) from with enhanced cellulase activities, achieved by engineering of enzyme -glycosylation sites in our previous studies, were used as components of the binary and ternary mixtures of cellulases in hydrolysis of Avicel and milled aspen wood. Using the engineered forms of the enzymes at a dosage of 10 mg/g substrate resulted in significant boosting of the glucose release from cellulose in the presence of excess β-glucosidase relative to the performance of the corresponding wild-type mixtures at the same loading. The boosting effects reached 11-40% depending on the reaction time and substrate type.

Blister formation during graphite surface oxidation by Hummers' method.

Graphite oxide has a complex structure that can be modified in many ways to obtain materials for a wide range of applications. It is known that the graphite precursor has an important role in the synthesis of graphite oxide. In the present study, the basal-plane surface of highly annealed pyrolythic graphite (HAPG) was oxidized by Hummers' method and investigated by Raman spectroscopy and atomic force microscopy.

Direct Observation of Changes in Focal Conic Domains of Cholesteric Films Induced by Ultraviolet Irradiation.

The helical supramolecular structure of cholesteric liquid crystalline (LC) films predetermines their outstanding optical properties and the unique nanostructure of their surface. The introduction of photochromic dopants in these films opens up an interesting possibility for creation of smart cholesteric materials with photocontrollable optical and photovariable surface properties. Using atomic force microscopy (AFM), we performed in situ measurements of the surface topography of cyclosiloxane LC cholesteric oligomer films during the cholesteric helix twisting caused by their preliminary ultraviolet (UV) irradiation.

Low doses of gamma-radiation induce SOS response and increase mutation frequency in Escherichia coli and Salmonella typhimurium cells.

This study addresses use of two bacterial test systems (the Ames test and the SOS chromotest) to estimate the effects of low doses of γ-radiation. The most substantial increases in induction of SOS response and mutation frequencies were observed in the first 24h of exposure to γ-radiation as compared to the cells in the exposure-free control. Gamma-radiation also impaired growth and survival of S.

Effect of N-linked glycosylation on the activity and other properties of recombinant endoglucanase IIa (Cel5A) from Penicillium verruculosum.

Endoglucanase IIa from Penicillium verruculosum (PvCel5A) has three potential N-glycosylation sites: Asn19, Asn42 and Asn194. In order to study the role of N-glycosylation, the wild type (wt) PvCel5A and its mutant forms, carrying Asn to Ala substitutions, were cloned into Penicillium canescens. All forms of the rPvCel5A were successfully expressed and purified for characterization.

2.3THz radiation: Absence of genotoxicity/mutagenicity in Escherichia coli and Salmonella typhimurium.

The mutagenicity and genotoxicity in bacteria of 2.3THz radiation (THz) produced by a free-electron laser (NovoFEL) were evaluated; exposures were 5, 10, or 15min at average power 1.4W/cm(2).

A Genetically Modified Tobacco Mosaic Virus that can Produce Gold Nanoparticles from a Metal Salt Precursor.

We genetically modified tobacco mosaic virus (TMV) to surface display a characterized peptide with potent metal ion binding and reducing capacity (MBP TMV), and demonstrate that unlike wild type TMV, this construct can lead to the formation of discrete 10-40 nm gold nanoparticles when mixed with 3 mM potassium tetrachloroaurate. Using a variety of analytical physicochemical approaches it was found that these nanoparticles were crystalline in nature and stable. Given that the MBP TMV can produce metal nanomaterials in the absence of chemical reductants, it may have utility in the green production of metal nanomaterials.

Surface Relief Changes in Cholesteric Cyclosiloxane Oligomer Films at Different Temperatures.

The development of new approaches for the surface topography control is an important topic as the relief significantly affects physical and chemical properties of surfaces. We studied cholesteric cyclosiloxane oligomeric films on which surface focal conic domains with double-helix pattern were observed by means of AFM. In situ investigation of the dependence of the films topography on temperature showed that the surface relief formation can be effectively managed by varying conditions of thermal treatment.