Synthesis of C-terminal peptide fragments of the heavy chain of hemagglutinin of influenza virus of subtypes H1 and H3

It is proposed to use the chromogenic 2-[4-phenylazo)benzylsulfonyl]ethyl group, which can be eliminated by organic bases in aprotic solvents, for the protection of a C-terminal carboxy group in the synthesis of peptides. The synthesis of a number of 10–16-membered peptides corresponding to C-terminal fragments of the heavy chain of the hemagglutination of influenza virus of subtypes H1 and H3 has been performed with the use of this group.All-Union Scientific-Research Institute of Molecular Biology, Kol'tsovo, Novosibirsk Oblast. Vektor Scientific-Industrial Association, Ministry of the Medical and Biological Industry of the USSR, Novosibirsk. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 732–738, September–October, 1988.     

Lanthiopeptin,a new peptide effective against herpes simplex virus: Structural determination and comparison with Ro 09-0198, an immunopotentiating peptide

The structure of lanthiopeptin, a new lanthionine peptide effective against Herpes virus, was newly determined. It has a unique tetracyclic sequence which is very similar to but different from the proposed structure for Ro 09-0198. However, Ro 09-0198 was found to be quite the same compound as lanthiopeptin in all respects.     

1, 2-, 1, 3- and 1, 4-Cyclohexanedicarboxylates of Cd and Mn with chain and layered structures

A systematic study has been carried out on the three isomeric cyclohexanedicarboxylates (CHDCs) formed by cadmium and manganese with the three isomeric dicarboxylic acids, in the presence or absence of amines. The CHDCs have been prepared under hydrothermal conditions and their structures established by X-ray crystallography. We have been able to isolate two-dimensional layered structures of 1,2-, 1,3- and 1,4-cyclohexanedicarboxylates and chain structures of 1,3- and 1,4-cyclohexanedicarboxylates. The infinite metal-oxygen-metal linkages are observed only in the case of the 1,2-dicarboxylate. In all the three isomeric cyclohexanedicarboxylates, the e,e conformation is most favored, although the 1,4-CHDCs often contain rings in both the e,e and the a,e conformations.     

Interfacial properties of a synthetic peptide derived from hepatitis G virus E2 protein: interaction with lipid monolayers

A useful approach to get information about the potential fusogenic ability of virus synthetic peptides is the study of its interfacial properties and subsequent study in mono- and bilayers. In this work, we have characterized by means of physicochemical tools (i.e. compression isotherms and surface activity) the sequence 267-284, LLGTEVSEVLGGAGLTGG, derived from the E2 structural protein of HGV/GBV-C. The adsorption of the peptide at the air/water interface was monitored by following the increase in surface pressure as a function of time at two different pH values: 5 and 7. Parameters such as surface excess or molecular area were calculated from the equation of Gibbs. The peptide showed a tendency to migrate to the surface of a saline-buffered solution. It formed stable monolayers at the air/water interface giving a compression isotherm with a shape consistent with that of some alpha-helical peptide conformations. Brewster angle microscopy (BAM) showed that through compression the peptide formed multilayers. The studies with lipid monolayers (DPMC, DMPC/DMPG, and DMPC/DMTAP) showed that the peptide interacts with all the lipids assayed producing a marked disrupting effect upon them. In these effects electrostatic interactions seem to have some participation.     

New N1-(4-aryloxybenzyl)uracils containing N3-positioned 4-(trimethyleneoxy)benzoic acid moiety,and study of their antiviral activity against SARS-CoV-2 and influenza virus

New title uracil derivatives, 4-{3-[2,6-dioxo-3-(4-aryl-oxybenzyl)-3,6-dihydropyrimidin-1(2H)-yl]propoxy}benzoic acids and their butoxy homologues, were obtained in three steps using 2,4-bis(trimethylsilyloxy)pyrimidine, 4-aryloxy-benzyl bromides and methyl 4-(ω-bromoalkoxy)benzoates as the key reactants. The compounds were studied as inhibitors of H1N1 influenza virus and SARS-CoV-2 R replication in MDCK and Vero E6 cell cultures, respectively, which revealed that the tested compounds had high levels of anti-SARS-CoV-2 activity.     

Identification and refinement of a peptide affinity ligand with unique specificity for a monoclonal anti-tenascin-C antibody by screening of a phage display library

Using phage display technology, a 22-mer peptide was selected as a ligand with unique specificity for the murine monoclonal ST2146 antibody that recognizes the EGF repeats region of the human tumor-associated antigen tenascin-C. This peptide, synthesized in an 8-branched form to enhance its binding properties, is useful in replacing the native antigen in the affinity and immunoreactivity characterization of the ST2146 antibody and its biotinylated derivatives. Affinity resins, prepared by immobilizing the mimotope or its shorter 10-mer binding unit on a chromatographic support, were able to capture ST2146 directly from the hybridoma supernatant, with antibody recovery and host cell protein (HCP) reduction similar to or better than protein A sorbent, a purity degree exceeding 95%, and full recovery of antibody activity. The affinity constants of both peptides, as determined by frontal analysis of broad-zone elution affinity chromatography and BiaCore measurements, were very similar and included in a range suitable for affinity ligands. Column capacity, determined by applying a large excess of purified ST2146 to 1 mL of column bed volume, was close to 50 mg/mL for both resins. These matrices retain their ST2146 binding properties after various treatments, including sanitization, thus indicating very high stability in terms of ligand leakage and degradation. Moreover, the short form shows higher enzymatic stability, thus proving more suitable as ligand for ST2146 affinity purification.     

Characterization of glycosylation sites for a recombinant IgG1 monoclonal antibody and a CTLA4-Ig fusion protein by liquid chromatography-mass spectrometry peptide mapping

Liquid chromatography mass spectrometry (LC-MS) peptide mapping can be a versatile technique for characterizing protein glycosylation sites without the need to remove the attached glycans as in conventional oligosaccharide mapping methods. In this way, both N-linked and O-linked sites of glycosylation can each be directly identified, characterized, and quantified by LC-MS as intact glycopeptides in a single experiment. LC-MS peptide mapping of the individual glycosylation sites avoids many of the limitations of preparing and analyzing an entire pool of released N-linked oligosaccharides from all sites mixed together. In this study, LC interfaced to a linear ion trap mass spectrometer (ESI-LIT-MS) were used to characterize the glycosylation of a recombinant IgG1 monoclonal antibody and a CTLA4-Ig fusion protein with multiple sites of N-and O-glycosylation. Samples were reduced, S-carboxyamidomethylated, and cleaved with either trypsin or endoproteinase Asp-N. Enhanced detection for minor IgG1 glycoforms (～0.1 to 1.0 mol% level) was obtained by LC-MS of the longer 32-residue Asp-N glycopeptide (4+ protonated ion) compared to the 9-residue tryptic glycopeptide (2+ ion). LC-MS peptide mapping was run according to a general procedure: (1) Locate N-linked and/or O-linked sites of glycosylation by selected-ion-monitoring of carbohydrate oxonium fragment ions generated by ESI in-source collision-induced dissociation (CID), i.e. 204, 366, and 292 Da marker ions for HexNAc, HexNAc-Hex, and NeuAc, respectively; (2) Characterize oligosaccharides at each site via MS and MSMS. Use selected ion currents (SIC) to estimate relative amounts of each glycoform; and (3) Measure the percentage of site-occupancy by searching for any corresponding nonglycosylated peptide.     

Specific and nonspecific interactions in a molecule with flexible side chain: 2-phenylethanol and its 1:1 complex with argon studied by high-resolution UV spectroscopy

Using high-resolution resonance-enhanced two-photon ionization spectroscopy in combination with genetic-algorithm-based computer-aided rotational fit analysis and ab initio quantum chemistry calculations we determined the conformational structure and transition moment orientation in 2-phenylethanol and its 1:1 clusters with argon. The results clearly demonstrate that the gauche structure of 2-phenylethanol, which is stabilized by the intramolecular pi-hydrogen bond between the folded side chain and the benzene ring, is the most abundant in the cold molecular beam. In this conformer the transition moment is rotated by 18 degrees from the short axis of the aromatic ring. Two distinct 1:1 complexes of 2-phenylethanol with argon in a cis- and trans-configuration with respect to the side chain have been found. Employing the Kraitchman [Am. J. Phys. 21, 17 (1953)] analysis we have found that the structure of the 2-phenylethanol moiety and the orientation of the transition moment do not change after the complexation with argon within the experimental accuracy. From the measured band intensities we conclude that in addition to the dispersion interaction of the argon atom with the aromatic ring a hydrogen-bond-type interaction with the terminal -OH group of the side chain stabilizes the cis-structure of the 1:1 complex of 2-phenylethanol with argon.     

Mechanistic and synthetic aspects of hydroboration with a simple atropisomeric ligand prepared from 1-(1′-(isoquinolyl)-2-naphthol

A novel triarylphosphite ligand has been prepared directly from both enantiomers of BINOL and a single enantiomer of 1′-(isoquinolyl)-2-naphthol. In one of the two cases cationic Rh complex proved to be reasonably effective in the asymmetric hydroboration of electron-poor styrenes. It was possible to identify binuclear reactive intermediates when the hydroboration pre-catalyst was examined in the presence of catecholborane at low temperatures.     

Influence of intermolecular interactions on the conformation of a 2-[bis(2-ethylphenyl)thiophosphorylhydroxymethyl]-1-ethylbenzimidazole molecule (L) upon complex formation with ZnCl2: Crystal and molecular structures of molecule L

The structures and conformations of a 2-[bis(2-ethylphenyl)thiophosphorylhydroxymethyl]-1-ethylbenzimidazole (L) molecule in the free form (L_fr) and in the [ZnCl₂L]L complex (I) are compared using the X-ray diffraction data. In complex I, one ligand molecule (L_c) is coordinated to the zinc atom in the bidentate chelating mode and the second molecule (L_solv) accomplishes the solvating function. An isomer with the cis orientation of the O(1) atom to the N(1) atom is observed in the crystal structure of L_fr, like L_solv in complex I, with the formation of the five-membered corrugated H-heterocycle OC₂NH. L_fr and L_solv molecules differ in the arrangement of the aromatic rings of the 2R substituent of benzimidazole. Crystalline compound L forms dimeric associates in which three conjugate H-rings are closed by a bifurcate intermolecular hydrogen bond: two five-membered ONC₂H rings and one planar four-membered N₂H₂ ring ((N(1)…N(1A), 3.705 and H(1)…H(1A) 2.67 Å). Unlike crystals of compound I with the π-π-stacking interaction between the planar-parallel aromatic rings of benzimidazole of the L_solv and L_c molecules, the crystals of L have no similar interaction between the L_fr molecules.     

Generation of 3-(1H-pyrrol-3-yl)-1H-inden-1-ones via a tandem reaction of 1-(2-alkynylphenyl)-2-enone, 2-isocyanoacetate, and water

A silver triflate-catalyzed tandem reaction of 1-(2-alkynylphenyl)-2-enone, 2-isocyanoacetate, and water provides a novel and efficient route for the delivery of 3-(1H-pyrrol-3-yl)-1H-inden-1-ones. Four bonds are formed during the tandem process.     

含1, 6-二(4'-吡啶基)-2, 5-二氮杂己烷的一维链状和二维网状 银(I)超分子配 合物的合成与结构

本文报道了一种新型四齿配体L：1,6-二(4'-吡啶基)-2,5-二氮杂己烷的合成,及其与银(I)的超分子配合物的一维链状和二维网状的结构。     

Structural, energetic, and spectroscopic features of lower energy complexes of superoxide hydrates O2(-)(H2O)(1-4)

The lower-energy portions of the potential energy surfaces of superoxide hydrates O2(-)(H2O)(1< or = n < or = 4) are thoroughly investigated at high computational levels. The structural, energetic and spectroscopic features of the stable superoxide hydrates on these potential energy surfaces are discussed, focusing in particular on some implications to their infrared spectra and the hydrogen bond trends. The present work reports the transition-state linkers between the most stable superoxide hydrates which are useful to understand the energetics of their mutual interconversions.     

Complexes of CuII,NiII, and CoII with 2-cyano-2-(1-oxyl-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-2-yl)-1-R-ethylenolates

Copper(ii), nickel(ii), and cobalt(ii) complexes with deprotonated enaminoketone derivatives of 2-imidazoline nitroxide were synthesized. Their crystal structures were established by X-ray diffraction analysis, and their magnetic properties were investigated. All complexes exhibit strong (40—110 cm^–1) intramolecular ferromagnetic exchange interactions.     

Soft chemistry synthesis, crystal structure and 3D-AFM-micro-structural surface features of calcium-barium selenate molecule with AB2X5 structure

Acetate-citrate precursors were applied to synthesize amorphous gelatinous calcium barium selenate with molecular formula (Ca_0.5Ba_0.5Se₂O₅). The gel-product was sintering at 800°C for 2 hrs then well characterized by X-ray diffraction, SEM and EDX elemental analyses and proved that the product Ca_0.5Ba_0.5Se₂O₅ is mainly belong to AB2X5-type structure with average grain size ranged in between 1.2?C3.8 ??m. A visualized study was constructed depending upon SEM and 3D-AFM experimental data to confirm the the microstructure morphological features of calcium-barium selenate surface.     

Reactions of diazoalkanes with unsaturated compounds 7. Catalytic cyclopropanation of 1-alkoxy-, 1-acetoxy-, and 1-(trimethylsilyloxy)buta-1,3-dienes with diazomethane

Cyclopropanation of 1-butadienyl ethers or esters with diazomethane proceeds selectively in the presence of (PhCN)₂PdCl₂, as opposed to CuCl, at the less polar terminal double bond in these dienes when the molar proportions of reactants and catalyst are 1 (1.3–2) (0.002–0.005) to give the 2-cyclopropylvinyl ethers or esters in yields of 80–85%.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2746–2752, December, 1989.For previous communication, see [1].     

Totally selective reaction of CO2 with enantiopure amino epoxides under mild reaction conditions. synthesis and synthetic applications of enantiopure (4R,1'S)- or (4S,1'S)-4-(1-Aminoalkyl)-2-oxo-1,3-dioxolanes

The reaction of chiral (2R,1'S)- or (2S,1'S)-2-(1-aminoalkyl)epoxides 1 or 2 with CO2, generated from acidic treatment of an aqueous solution of NaHCO3 at room temperature, efficiently afforded enantiopure cyclic carbonates 3 or 4, respectively, with total selectivity. Compounds 3 and 4 were readily transformed into the corresponding diols 7 and 8 by reaction with LiAlH4 or by basic hydrolysis. When compounds 3 or 4 were allowed to react with methyllithium at -78 degrees C, O1-acetylalkane-1,2-diols 9 and 10 were obtained with total or high selectivity.     

Conjugated 1 beta-hydroxycholic acid in the urine of newborns and pregnant women measured by radioimmunoassay using antisera raised against N-(1 beta-hydroxycholyl)-2-aminopropionic acid-bovine serum albumin conjugate.

Anti-tauro 1 beta-hydroxycholic acid antisera were prepared by immunizing rabbits with N-(1 beta,3 alpha, 7 alpha, 12 alpha-tetrahydroxy-5 beta-cholan-24-oyl)-2- aminopropionic acid-bovine serum albumin (BSA) conjugate. The antisera raised had high affinity (1.25-1.46 x 10(9) M-1) and specificity for conjugated 1 beta-hydroxycholic acid; cross-reactivity for glyco 1 beta-hydroxycholic acid was 100% and that for the glycine and taurine conjugates of other 1 beta-hydroxylated bile acids ranged from 11.30 to 0.23%. Urinary concentrations of conjugated 1 beta-hydroxycholic acid were determined by radioimmunoassay in newborns, 0-20 d after birth, in amounts ranging from 0.29 to 18.51 micrograms/ml and in women in late pregnancy (less than 1.13 micrograms/ml), as well as in normal women (less than 0.12 microgram/ml).