Antioxidant Activity of Bioactive Peptide Fractions from Germinated Soybeans Conjugated to Fe3O4 Nanoparticles by the Ugi Multicomponent Reaction

The conjugation of biomolecules to magnetic nanoparticles has emerged as promising approach in biomedicine as the treatment of several diseases, such as cancer. In this study, conjugation of bioactive peptide fractions from germinated soybeans to magnetite nanoparticles was achieved. Different fractions of germinated soybean peptides (>10 kDa and 5–10 kDa) were for the first time conjugated to previously coated magnetite nanoparticles (with 3-aminopropyltriethoxysilane (APTES) and sodium citrate) by the Ugi four-component reaction. The crystallinity of the nanoparticles was corroborated by X-ray diffraction, while the particle size was determined by scanning transmission electron microscopy. The analyses were carried out using infrared and ultraviolet–visible spectroscopy, dynamic light scattering, and thermogravimetry, which confirmed the coating and functionalization of the magnetite nanoparticles and conjugation of different peptide fractions on their surfaces. The antioxidant activity of the conjugates was determined by the reducing power and hydroxyl radical scavenging activity. The nanoparticles synthesized represent promising materials, as they have found applications in bionanotechnology for enhanced treatment of diseases, such as cancer, due to a higher antioxidant capacity than that of fractions without conjugation. The highest antioxidant capacity was observed for a >10 kDa peptide fraction conjugated to the magnetite nanoparticles coated with APTES.     

Synthesis and characterization of two novel tin(IV) compounds containing 12‐membered metallarings

12‐Chloro‐12‐n‐butyl‐1,11‐dioxa‐4,8‐ dithia‐12‐stannacyclododecane ( 3a ) and 12‐chloro‐ 12‐n‐butyl‐1,4,8,11‐tetrathia‐12‐stannacyclododecane ( 3b ) have been prepared by reacting n‐butyltin trichloride with 1,11‐dioxa‐4,8‐dithiaundecane and 1,4,8,11‐tetrathiaundecane, respectively. Complexes 3a,b were characterized by elemental analyses, IR, electron impact mass spectrometry, and multinuclear NMR (¹H, ¹³C, and ¹¹⁹Sn). The spectroscopic data are consistent with bonding of the ligands through both sulfur and oxygen atoms in 3a and through all sulfur atoms in 3b to the Sn(IV) center. We suggest hexacoordination around the Sn atoms. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:451–453, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20040     

Modification of PP fibres with alkaline copolyamides

Copolyamides with 5.9‐19.7 wt.% of nylon salt ADETA (adipic acid + diethylenetriamine) and 94.1‐80.3 wt.% of ϵ‐caprolactam were synthesized and their properties were estimated. Blended polypropylene/copolyamides fibres containing 5‐15 wt.% of copolyamides were prepared and their properties were evaluated. The electrical properties, hydrophilicity and especially dyeability of modified PP fibres are positively influenced by a higher amount of the copolyamide in the PP and also by a higher amount of the nylon salt ADETA in the copolyamide.     

Matrix-assisted laser desorption/ionization tandem reflectron time-of-flight mass spectrometry of fullerenes

Atandem reflectron time-of-flight mass spectrometer developed in our laboratory provides a unique opportunity to investigate the collision-induced dissociation of fullerene ions formed by matrix-assisted laser desorption/ionization (MALDI). Specifically, this opportunity arises from the ability to utilize high energy collisional activation (normally available only on tandem sector instruments by using continuous ionization techniques) for ions formed by pulsed laser desorption, whereas most MALDI time-of-flight instruments record product ion mass spectra of ions formed by metastable or postsource decay. In this study we investigate the products of mass-selected and collisionally activated C ₆₀ ⁺ and C ₇₀ ⁺ ions by using different target gases over a range of target gas pressures. In general, heavier target gases produce more extensive fragmentation and improve the mass resolution of lower mass ionic products because a greater portion of these ions are formed by single collisions. Additionally, the tandem time-of-flight instrument utilizes a nonlinear (curved-field) reflectron in the second mass analyzer that enables high energy collision-induced dissociation spectra to be recorded without scanning or stepping the reflectron voltage.     

Conformational changes of strong polycations in the presence of divalent counterions and their influence upon the flocculation efficiency

The interaction between strong polycations, which possess the ammonium quaternary centers attached to an acrylic macromolecular chain derived from poly(N,N-dimethylaminoethyl methacrylate) (polycations Q_x), and divalent counterions was investigated by viscometry and turbidimetry. Conformational changes of polycations were influenced by the polycation charge density, counterion nature (SO₄²⁻ or S₂O₈²⁻) and concentration. The morphology of the polycation layers deposited onto silicon wafers has been studied by tapping mode atomic force microscopy, a strong influence of the polycation and ammonium persulfate concentration on the surface topography being observed. The optimum flocculation concentration of polycation decreased and the flocculation window increased in the presence of S₂O₈²⁻, in the destabilization of kaolin model dispersion. Removal of Congo Red from aqueous solution by the complex system formed between polycations and divalent counterions was also investigated. The behavior of polycations Q_x in separation processes was compared with that of one polycation containing 95 mol% N,N-dimethyl-2-hydroxypropyleneammonium chloride units in the backbone (PCA₅).     

Further Studies on Homo- and Copolymerization of Styrene through Metallocenic Initiator Systems

Summary: Binary metallocene-MAO and ternary diphenylzinc-metallocene-MAO initiator systems have been tested as initiators in the homopolymerization of styrene and also in its copolymerization with several diverse comonomers including substituted styrenes, styrene derivatives, α-olefins and dienes. Various titanocenes and zirconocenes and some exploratory experiment with hafnocene were carried out. The results indicate that titanocenes were more effective than zirconocenes in the homopolymerization of styrene while zirconocenes did better in α-olefin polymerization. It was found that titanocenes generated mainly syndiotactic polystyrene, s-PS, while zirconocenes yielded atactic polystyrene or, depending on the zirconocene, a low percentage of s-PS. For these types of initiators the polymerization process depends largely on the inductive effect of the substituents linked to the benzene ring of styrene and on its position (ortho, meta or para). Substituent multiplicity reduced markedly the effectiveness of these initiator systems. Styrene/isoprene polymerization was also studied using binary zirconocene-MAO initiator systems that yielded low conversions and also low molecular weight polymers.     

The unitarizability of the Aubert dual of strongly positive square integrable representations

Under a natural assumption, which holds in the generic case, we prove in this paper that, for the classical p-adic groups, the Aubert dual of an irreducible, strongly positive square-integrable representation (in the sense of Mœgl., in-Tadić classification), is unitarizable. In this way, for this important class of representations, we verify the conjecture which states that the Aubert involution preserves unitarity.     

Are the mixtures of homologous surfactants ideal?

The interaction between homologous surfactants in mixed micelles was studied by the Regular Solution Theory of mixed micelles. The interaction is independent of the nature of the polar head groups and attractive and the interaction parameter betaM depends linearly on the difference in chain length DeltanC. The interaction becomes ideal at DeltanC=0.75+/-0.06. Above DeltanC approximately 5, the dependence remains linear but the slope increased 2.7 times. The phenomenon is explained as the effect of the reduction of the hydrocarbon/water micelle interface and a better packing of the chains in the micelle core, caused by the inclusion of a shorter homologous surfactants. This reduction can be more effective when DeltanC>or=5.     

Light-induced flipping of a conserved glutamine sidechain and its orientation in the AppA BLUF domain

The AppA BLUF domain is a blue light photoreceptor containing flavin. Conserved glutamine 63 is necessary for the photocycle of the protein, and its side chain has been proposed to flip in response to blue light illumination. Recently published crystal structures of AppA WT and the AppA mutant C20S describe contradictory conclusions regarding the orientation of the conserved glutamine 63 side chain in the dark. Here, we present evidence from NMR spectroscopy confirming light-induced flipping of the glutamine side chain to form a strong hydrogen bond between the glutamine 63 side chain carbonyl group and the tyrosine 21 side chain hydroxyl proton in the light-induced state. Our conclusions are consistent with published data from UV/vis absorbance and FTIR spectroscopy, as well as the crystal structure of AppA WT.