Modification of β2 I by glutardialdehydeI by glutardialdehyde

Autoantibodies from patients with antiphospholipid syndrome (APS) recognize an epitope on β₂glycoprotein I (β₂GPI) only when native β₂GPI is adsorbed on surfaces composed of anionic phospholipids or oxidized polystyrene, β₂GPI was modified with the crosslinking agent, glutardialdehyde (GDA), which induced exposure of the anti-β₂GPI epitope at GDA: β₂GPI mol ratios in the range of 500–2000. A second crosslinking agent, dimethyl-suberimidate (DMS), did not expose the epitope, which may be a consequence of its having less tendency than GDA to form intermolecular links. SDS-PAGE experiments demonstrate that GDA does promote extensive intermolecular crosslinking of β₂GPI, and DMS does not. Formaldehyde also reacts with the lysine residues of β₂GPI, but does not expose the epitope. The circular dichroism spectra of native and modified β₂GPI confirm that GDA induces changes in conformation that are qualitatively different from those caused by formaldehyde. These data provide evidence that binding of lysine residues is not a sufficient condition for exposure of the autoepitope, and also support the likelihood that β₂GPI antibodies bind only to aggregates of the protein. Thus, by synthesizing an active holoantigen of β₂GPI, conditions were defined that are necessary for binding of human autoantibodies. The authors also suggest that treatment of phospholipid-binding proteins with chemical agents might provide a strategy to modify their structure and permit exposure of epitopes, resulting in synthetic antigens for therapeutic and diagnostic use.     

Characterization of Galactosyl-neoglycoalbumin by MALDI-TOF-MS

Matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS, model AXIMA CFR ) was used to analyze galactosyl-HSA (human serum albumin) synthesized in our laboratory. It clearly showed that HSA covalently combined with galactoses. Galactosyl-HSA is pure and the ratio of galactosyl residues to protein is 48:1.     

A Novel Synthesis of Dimethyl Malonate by Carbonylation of Methyl Chloroacetate Catalyzed by Cobalt Complex

Dimethyl malonate (DMM) is an important organic synthesis intermediate. Traditional synthetic method by reaction of mono-chloroacetic acid with sodium cyanide1 is poisonous and complicated. Therefore, an interest in green synthesis routes of DMM has risen greatly. The several processes for preparing DMM by carbonylation of methyl chloroacetate catalyzed by Co2(CO)8 have been reported2~5. However, Co2(CO)8 is unstable and must be prepared under high pressure (12 Mpa). Moreover, the yield…     

The Hydrolysis of RNA by Histidine

DNAand~cleaVagagentshavereCeedconsi~eattentionfOtmultiPePUrPOSeS,SUchastheamegyintheuseofedenseOligOnuCleotidestaforbeSelectivechonofgeneexPessiOlll,2).SmallmOleculeswithmorDNACleaVag~areodasresearChtoolsfO1theinvestighonOfnUCleaCidsStrUCtUres(3,4)andmpbeusefulinnuCeiceddsseqUenCing(5).NeWaPPlicationinmOeculaxbiOlQgybePrgnOtedthedevelqPmenofCatalyStSthatareeff~undermildconditions.S~exmpesOfoalhodeaVag~havborpeed(6).Theagents~eofwibydIobosofPh~bondbeteenstudiedext~dUetoth…     

Surface Modification of Montmorillonites by Chlorosilanes

Montmorillonite was modified by chlorosilane derivatives (trimethylchlorosilane and tert-butyldimethylchlorosilane)based on the reaction between OH group and chlorosilane,Fourier-transformed infrared spectra(FTIR)confirmed that chlorosilanes did react with the OH groups of montmorillonite.The effect of reaction time and dispersing agents on the intercalation was studied by wide angle X-ray diffraction(WAXD) method.Further experiments proved that there is no reactive OH group on the surface of layers in the interlayer galleries of montmorillonite.The cation exchange capacity(CEC) of montmorillonites was measured.showing that after modification by chlorosilane derivatives,CEC values drastically decreased.The dispersibility measurements of montmorillonites were conducted.which showed that the dispersibility of modified montmorillonites both in H2O and toluene wer improved due to the decrease of attractions of particles and layers.     

Preparation of D-Phenylalanine by Asymmetric Transformation

The method of preparing D-phenylalanine by asymmetric transformation is reported.D-phenylalanine was prepared from DL-phenylalanine by two-step reaction.D-phenylalanine(2S,3S)-tartrate was prepared by heating DL-phenylalanine,salicylaldehyde,and (2S,3S)-tartaric acid in propionic acid;the obtained D-phenylalanine(2S,3S)-tartrate was treated with triethylamine in ethanol giving D-phenylalanine with 98% optical purity in 69% yield.     

Synthesis of β-Lactams by Convenient Annelation of Imines

2-Acyl-3-oxo-4,5-benzo-1,2-thiazoline 1,1-dioxide (3) provides good yield routes to monocyclic 3-lactams (6) and tricyclic β-lactams (7) from a variety of imines (4) and 1-substituted-3,4-dihydroisoquinolines (5).     

Characterization of Galactosyl-neoglycoalbumin~1 by MALDI-TOF-MS

It was reported there was a membrane receptor, hepatic binding protein (HBP), which resides only at the cell surface of mammalian hepatocytes, selectively bind galactose- terminated glycoprotein for transporting to hepatic lysosomes1. According to this discovery, a special analog ligand, galactosyl-neoglycoalbumin(NGA), was prepared as hepatic targeting drug carrier and hepatic screening agents. The ligand was synthesized by covalent coupling of carbohydate bifunctional reagent, 2-imino-2-et…     

Synthesis of Stable σ-Adducts by Arylation of Quinazoline

Russian Journal of General Chemistry - The reactions of quinazoline with 1,3,5-trimethoxybenzene, 3- and 4-methylbenzene-1,2-diamines, and 1-(4-methoxybenzylidene)-2-phenylhydrazine on heating in...     

Enumeration of isomers of alkylcyclopropanes by means of alkyl 1,1‐biradicals

Henze and Blair [2] have successfully derived algorithms for enumerating the number of constitutional isomers of aliphatic compounds using alkyl radicals; however, the algorithms cannot be extended to enumerate constitutional isomers of cyclic compounds. Similarly, Read [4] has advocated the use of alkyl biradicals to enumerate constitutional isomers of aliphatic compounds, but not cyclic compounds. Apparently, the use of alkyl biradicals in the enumeration of constitutional isomers of cyclic compounds has been neglected. In this communication, an algorithm using alkyl biradicals to enumerate the number of constitutional isomers of cyclic compounds, namely alkylcyclopropanes, is described. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis of the Active Stilbenoids by Photooxidation Reaction of trans-e-Viniferin

Introduction It was reported that stilbene monomers showed multi-faced biological activities, such as antioxidation, antimutagen, antibacterial, antifungal activities.1 Espe-cially, isorhapontigenin and resveratrol showed potent inhibition on biosynthesis of leukotriene and its receptor antagonist.2 Some oligostilbenes exhibited more potent bioactivities than their monomers.3 In recent years, a number of oligostilbenes were isolated from natural sources, but a few of studies on their pharmacol…     

Determination of selectivity of HPLC systems by correspondence factor analysis

Correspondence factor analysis （CFA） was employed to study the selectivity of 14 HPLC systems. The tested LC systems were classified as reversed-phase （RP）, ion-exchange （IE） and hydrophilic interaction chromatography （HILIC） modes. It was found that the retentions of the hydrophilic solutes on HILIC column were significantly influenced by the second-order effects besides their hydrophilic properties. Organic modifiers and residue silanol groups on silica surface both participated in retention. HypersilTM amino column performed separation in the HILIC mode at appropriate conditions, and its retention mechanism was more similar to that of HILIC silica column than that of HILIC column coating poly（aspartamide） groups.     

The Characterization of Comblike Polymer Electrolyte by Means of NMR

Polymer solid electrolytes are a class of solid materials whose properties lie betweenthose of solids and liquids, and they have been widely used in energy resources,. metallurgy, environmental protection, electro-chemistry device and so on' '2.Inoue had pointed out that polystyrene derivative with many poly (ethylene oxide)PEO side chain could make conductivity reach 10-' S/cm. They think that the flexibilityo f the backbone is not necessarily the impoFtant factor to achieve a high conducti…     

Microencapsulation of Fish Oil by Simple Coacervation of Hydroxypropyl Methylcellulose

To improve the oxidative stability and application of fish oil, it was microencapsulated by simple coacervation followed by spray drying. Simple coacervation took place by adding malt dextrin into the emulsion of fish oil and hydroxypropyl methylcellulose （HPMC） solution. Influences of several process parameters on the microencapsulation were evaluated and the oxidative stability and microstructure of microcapsules were analyzed. Results showed that the coacervation could be observed only when dextrose equivalent value （DE value） of malt dextrin, concentration of HPMC solution and fish oil percentage in microcapsules were no more than 20. 5% and 40%, respectively. Moreover, microencapsulation efficiency was higher at HPMC solution concentration of 4% and fish oil percentage of less than 30%. The oxidative stability of fish oil was improved by the microencapsulation and done best in the ease of replacing malt dextrin by 40% with acacia. Scanning electronic microscopic photographs showed that the microcapsule obtained was a round, smooth and hollow microcapsule with its wall made up of innumerable small and solid submicrocapsules with the core of fish oil.     

Synthesis of ω-Chloroalkylisocyanide Dichlorides by Thermolysis of Phosgeniminium Salts

Thermal ring-opening of heterocyclic phosgeniminium salts 1 affords either ω-chloroalkylisocyanide dichlorides 2a-f or N-trichloromethyl chloroformamidines 2g-i in very good yields.     

Formation of a Hydroxyperhydroindanone by Reductive Cyclization of γ-Cyanoketone

The reduction of nitrile with alkali metal-ammonia is known to produce amine or hydrocarbon. Arapokos and coworkers^1,2 had shown that such reduction of a tertiary nitrile gave exclusively the hydrocarbon resulting from decyanation, whereas primary and secondary nitrile gave both the amine and decyanation products. Such decyanation pathway can be suppressed in the presence of a proton source e.g. methanol³ and by the proper choice of metal⁴. It is assumed that the reduction of a primary or secondary nitrile to amine involves the intermediate anion (1).     

Formation of Stilbene Azo-Dimer by Direct Irradiation of p-Azidostilbene†

Triplet arylnitrenes may provide direct access to aryl azo-dimers, which have broad commercial applicability. Herein, the photolysis of p-azidostilbene ( 1 ) in argon-saturated methanol yielded stilbene azo-dimer ( 2 ) through the dimerization of triplet p-nitrenostilbene (³ 1N ). The formation of ³ 1N was verified by electron paramagnetic resonance spectroscopy and absorption spectroscopy (λ_max ~ 375 nm) in cryogenic 2-methyltetrahydrofuran matrices. At ambient temperature, laser flash photolysis of 1 in methanol formed ³ 1N (λ_max ~ 370 nm, 2.85 × 10⁷ s⁻¹). On shorter timescales, a transient absorption (λ_max ~ 390 nm) that decayed with a similar rate constant (3.11 × 10⁷ s⁻¹) was assigned to a triplet excited state (T) of 1 . Density functional theory calculations yielded three configurations for T of 1 , with the unpaired electrons on the azido (T_A) or stilbene moiety (T_Tw, twisted and T_Fl, flat). The transient was assigned to T_Tw based on its calculated spectrum. CASPT2 calculations gave a singlet–triplet energy gap of 16.6 kcal mol⁻¹ for 1 N ; thus, intersystem crossing of ¹ 1N to ³ 1N is unlikely at ambient temperature, supporting the formation of ³ 1N from T of 1 . Thus, sustainable synthetic methods for aryl azo-dimers can be developed using the visible-light irradiation of aryl azides to form triplet arylnitrenes.     

Synthesis of (−)-benzolactam-V8 by application of asymmetric aziridination

(?)-Benzolactam-V8, an artificially-designed cyclic dipeptide with strong tumor-promoter activity, was synthesized from benzyl (S)-N-(2-formylphenyl)-N-methylvalinate by application of guanidinium ylide-participated asymmetric aziridination followed by the reductive ring-opening reaction of 3-arylaziridine-2-carboxylate formed.     

Cyclization of N-allylthiourea derivatives by the action ofα-chloronitrosoalkanes

A convenient method is proposed for obtaining difficultly available derivatives of 2-amino-5-chloromethyl-2-thiazoline by the cyclization of N-allythioureas under the action of-chloronitrosoalkanes. It is assumed that the reaction proceeds as a halogenophilic process leading to the intermediate formamidinesulfenyl chloride which is rapidly and selectively cyclized with the formation of 2-amino-2-thiazoline derivatives.Institute of Physiologically Active Substances, Russian Academy of Sciences, Chernogolovka 142432, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 381–384, March, 1998.