bluuebunny/crossref_metadata_2025 huggingface dataset:
CD147/EMMPRIN Acts as a Functional Entry Receptor for Measles Virus on Epithelial Cells
Authors: Watanabe Akira , Yoneda Misako , Ikeda Fusako , Terao-Muto Yuri , Sato Hiroki , Kai Chieko
Published: February 2010

Measles is a highly contagious human disease caused by measles virus (MeV) and remains the leading cause of death in children, particularly in developing countries. Wild-type MeV preferentially infects lymphocytes by using signaling lymphocytic activation molecule (SLAM), whose expression is restricted to hematopoietic cells, as a receptor. MeV also infects other epithelial and neuronal cells that do not express SLAM and causes pneumonia and diarrhea and, sometimes, serious symptoms such as measles encephalitis and subacute sclerosing panencephalitis. The discrepancy between the tissue tropism of MeV and the distribution of SLAM-positive cells suggests that there are unknown receptors other than SLAM for MeV. Here we identified CD147/EMMPRIN (extracellular matrix metalloproteinase inducer), a transmembrane glycoprotein, which acts as a receptor for MeV on epithelial cells. Furthermore, we found the incorporation of cyclophilin B (CypB), a cellular ligand for CD147, in MeV virions, and showed that inhibition of CypB incorporation significantly attenuated SLAM-independent infection on epithelial cells, while it had no effect on SLAM-dependent infection. To date, MeV infection was considered to be triggered by binding of its hemagglutinin (H) protein and cellular receptors. Our present study, however, indicates that MeV infection also occurs via CD147 and virion-associated CypB, independently of MeV H. Since CD147 is expressed in a variety of cells, including epithelial and neuronal cells, this molecule possibly functions as an entry receptor for MeV in SLAM-negative cells. This is the first report among members of the
Mononegavirales
that CD147 is used as a virus entry receptor via incorporated CypB in the virions.
Structure-Based Mutational Analysis of the Bovine Papillomavirus E1 Helicase Domain Identifies Residues Involved in the Nonspecific DNA Binding Activity Required for Double Trimer Formation
Authors: Liu Xiaofei , Schuck Stephen , Stenlund Arne
Published: February 2010

The papillomavirus E1 protein is a multifunctional initiator protein responsible for preparing the viral DNA template for initiation of DNA replication. The E1 protein encodes two DNA binding activities that are required for initiation of DNA replication. A well-characterized sequence-specific DNA binding activity resides in the E1 DBD and is used to tether E1 to the papillomavirus ori. A non-sequence-specific DNA binding activity is also required for formation of the E1 double trimer (DT) complex, which is responsible for the local template melting that precedes loading of the E1 helicase. This DNA binding activity is very poorly understood. We use a structure-based mutagenesis approach to identify residues in the E1 helicase domain that are required for the non-sequence-specific DNA binding and DT formation. We found that three groups of residues are involved in nonspecific DNA binding: the E1 β-hairpin structure containing R505, K506, and H507; a hydrophobic loop containing F464; and a charged loop containing K461 together generate the binding surface involved in nonspecific DNA binding. These residues are well conserved in the T antigens from the polyomaviruses, indicating that the polyomaviruses share this nonspecific DNA binding activity.
Generation of the Pathogenic R5-Tropic Simian/Human Immunodeficiency Virus SHIV
AD8
by Serial Passaging in Rhesus Macaques
Authors: Nishimura Yoshiaki , Shingai Masashi , Willey Ronald , Sadjadpour Reza , Lee Wendy R. , Brown Charles R. , Brenchley Jason M. , Buckler-White Alicia , Petros Rahel , Eckhaus Michael , Hoffman Victoria , Igarashi Tatsuhiko , Martin Malcolm A.
Published: February 2010

A new pathogenic R5-tropic simian/human immunodeficiency virus (SHIV) was generated following serial passaging in rhesus macaques. All 13 animals inoculated with SHIV
AD8
passaged lineages experienced marked depletions of CD4
+
T cells. Ten of these infected monkeys became normal progressors (NPs) and had gradual losses of both memory and naïve CD4
+
T lymphocytes, generated antiviral CD4
+
and CD8
+
T cell responses, and sustained chronic immune activation while maintaining variable levels of plasma viremia (10
2
to 10
5
RNA copies/ml for up to 3 years postinfection [p.i.]). To date, five NPs developed AIDS associated with opportunistic infections caused by
Pneumocystis carinii
,
Mycobacterium avium
, and
Campylobacter coli
that required euthanasia between weeks 100 and 199 p.i. Three other NPs have experienced marked depletions of circulating CD4
+
T lymphocytes (92 to 154 cells/μl) following 1 to 2 years of infection. When tested for coreceptor usage, the viruses isolated from four NPs at the time of their euthanasia remained R5 tropic. Three of the 13 SHIV
AD8
-inoculated macaques experienced a rapid-progressor syndrome characterized by sustained plasma viremia of >1 × 10
7
RNA copies/ml and rapid irreversible loss of memory CD4
+
T cells that required euthanasia between weeks 19 and 23 postinfection. The sustained viremia, associated depletion of CD4
+
T lymphocytes, and induction of AIDS make the SHIV
AD8
lineage of viruses a potentially valuable reagent for vaccine studies.
CD317/Tetherin Is Enriched in the HIV-1 Envelope and Downregulated from the Plasma Membrane upon Virus Infection
Authors: Habermann Anja , Krijnse-Locker Jacomine , Oberwinkler Heike , Eckhardt Manon , Homann Stefanie , Andrew Amy , Strebel Klaus , Kräusslich Hans-Georg
Published: February 2010

CD317/Bst-2/tetherin is a host factor that restricts the release of human immunodeficiency virus type 1 (HIV-1) by trapping virions at the plasma membrane of certain producer cells. It is antagonized by the HIV-1 accessory protein Vpu. Previous light microscopy studies localized CD317 to the plasma membrane and the endosomal compartment and showed Vpu induced downregulation. In the present study, we performed quantitative immunoelectron microscopy of CD317 in cells producing wild-type or Vpu-defective HIV-1 and in control cells. Double-labeling experiments revealed that CD317 localizes to the plasma membrane, to early and recycling endosomes, and to the trans-Golgi network. CD317 largely relocated to endosomes upon HIV-1 infection, and this effect was partly counteracted by Vpu. Unexpectedly, CD317 was enriched in the membrane of viral buds and cell-associated and cell-free viruses compared to the respective plasma membrane, and this enrichment was independent of Vpu. These results suggest that the tethering activity of CD317 critically depends on its density at the cell surface and appears to be less affected by its density in the virion membrane.
Quantum chemical prediction of 2H-pyran vibration spectrum
Authors: Böhm Stanislav , Kuthan Josef
Published: February 2010

Ab initio MO optimalization of the 2H-pyran molecule leads to a defined equilibrium geometry of this so far not identified heterocyclic molecule and to a physical justification of its existence. More advanced nonempirical wavefunctions and temperature corrections indicate that heterocyclic molecule I is energetically less stable than non-cyclic isomers II and III. Wavenumbers of fundamental vibrational transitions of heterocycle I and also known (2E)-2,4-pentadienal (IIIb were calculated using 3-21 G wavefunctions. The vibrational spectrum of compound I is predicted on the basis of correlation corrections.
A result of resonant energy exchange between reactants and their chemical surrounding: The isokinetic relationship
Authors: Linert Wolfgang
Published: February 2010

Many homologous series of reactions exhibit a common point of intersection in the ln k versus 1/T plots. This can be taken as a profound basis for the appearance of the isokinetic relationship (IKR) defining a temperature where rate (or equilibrium) constants of the series show a minimum in selectivity. The theoretically derived relationship describing the IKR and yielding a correlation between the isokinetic temperature and the frequencies available in an ideal heat bath is examined for real systems. It is shown that the role of the solvent in chemical reactions that exhibit isokinetic relationship is not only due to chemical interactions but also to energy transfer between reactants and solvents and vice versa.
Determination of number of linear latent variables in a set of experimental chemical data
Authors: Pytela Oldřich
Published: February 2010

A criterion has been suggested for determination of number of linear latent variables in experimental chemical sets which is based on the principle of scatter analysis applied to the method of conjugated deviations. The criterion suggested has been tested on data with preliminarily given error, and correct numbers of latent variables were obtained until the error load 70%. The phenomenon of dominance of latent variables with the maximum variability has been analyzed and tested. The criterion suggested has been applied to three classes of data sets - homogeneous complete, homogeneous incomplete and nonhomogeneous incomplete. A good accordance with other criteria has been obtained first of all for the first data class, in most cases the found numbers of latent variables agreed with the experiment interpreted.
Principal component analysis of substituent constants
Authors: Hnyk Drahomír
Published: February 2010

The principal component analysis has been applied to a data matrix formed by 7 usual substituent constants for 38 substituents. Three factors are able to explain 99.4% cumulative proportion of total variance. Several rotations have been carried out for the first two factors in order to obtain their physical meaning. The first factor is related to the resonance effect, whereas the second one expresses the inductive effect, and both together describe 97.5% cumulative proportion of total variance. Their mutual orthogonality does not directly follow from the rotations carried out. With the help of these factors the substituents are divided into four main classes, and some of them assume a special position.
Synthese und UV/VIS-spektroskopische eingenschaften solvatochromer and halochromer methansulfonyl-substituierter pyridinium-N-phenolat-betainfarbstoffe
Authors: Reichardt Christian , Schäfer Gerhard , Milart Piotr
Published: February 2010

Synthese und UV/VIS-spektroskopische Eingenschaften der negativ solvatochromen, methansulfonyl-substituierten Betainfarbstoffe Ic-Ie werden beschrieben. Die lineare Korrelation zwischen den ET-Werten des wasserloslischen Betains Ic und den ET(30)-Werten des Standardbetains Ia erlaubt eine Erweiterung der empirischen ET(30)-Polaritatsskala auf wassrige Elektrolytlosungen. Die Betaine Ic-Ie weisen eine negative Halochromite (Halo-Solvatochromie) auf. Eine neue Definition der Halochromie (Halo-Solvatochromie) wird gegeben.
Further studies an the extended Hammett equation comprising the hydrophobic constant: Reactivity data for benzoic acids, arylacetic acids, β-arylpropionic acids, trans- and cis-cinnamic acids, methyl benzoates; dissociation constants, DDM reaction and alkaline hydrolysis in various water-organic solvent mixtures
Authors: Hoefnagel Anthonius J. , Wepster Bartholomeus M.
Published: February 2010

The extended Hammett eguaition Δ = ρs + hπ comprising the hydrophobic constant π is found to be effective in the title compounds and reactivities in various solvent mixtures. In 32 vol.% tert-butanol-water hmdecreases in the order ArCOOMe (-0.25), cis-ArCH=CHCOOH (-0.18), ArCOOH and ArCH2COOH (-0.16), ArCH2CH2COOH and trans-ArCH=CHCOOH (-0.07). For ArCOOH, mixtures like 40-60% methanol, 50% ethanol, 50% acetone and 50% dioxane give similar hm values of circa -0.05. For ArCH2COOH the effects of 3-iodo and 4-iodo substituents are acid-weakening in 32% tert-butanol. The consequences of the hπ term for ρ, σ, and the averaging of σ values, are discussed.
13C and 15N NMR spectra of oximes prepared by nitrosation of activated methylene group
Authors: Jirman Josef , Lyčka Antonín , Ludwig Miroslav
Published: February 2010

15N and 13C NMR spectra have been measured of the compounds type XC(=NOH)Y, where X, Y = COCH3, CN, COOR, CONHR, and X +Y = C6H4(CO)2. The (E)-(Z) isomerism at the C=NOH bond has been studied by means of 15N labelling and stereospecific behaviour of the 2J(15N, 13C) coupling constants. The nitrosation of methyl cyanoacetate gives specifically the respective (E)-oxime, whereas that of acetoacetanilide gives the (Z)-isomer. The nitrosation of ethyl acetoacetate gives both (E)- and (Z)-oximes in a ratio of ca 1:10; the (E)-isomer is less stable and is transformed into the (Z)-isomer. The applicability of the 1J(13C, 13C) coupling constants and lanthanoid shift reagents to the study of (E)-(Z) isomerism of oximes with geminal carbonyl groups has also been verified. The 15N NMR chemical shifts of the oximes studied correlate with their respective pKa values measured in dimethyl sulfoxide according to the equation pKa = -0.11δ15N + 13.44.
Distinction of 3-(N,N-dimethylamino)coumarin from hypothetic 2-(N,N-dimethylamino)-1,3-indanedione by infrared spectroscopy
Authors: Perjéssy Alexandr , Donovalová Jana , Gáplovský Anton , Hrnčiar Pavol
Published: February 2010

A detailed investigation of infrared spectra was used to distinguish the structure of 3-(N,N-dimethylamino)coumarin from the structure of hypothetic 2-(N,N-dimethylamino)-1,3-indanedione suggested earlier as the product of the reaction between salicylaldehyde, acetanhydride and betaine.
NMR studies of 1-phenylazo-3-substituted-2-naphthols in solution and in the solid state
Authors: Lyčka Antonín , Nečas Miroslav , Jirman Josef , Straka Jaroslav , Schneider Bohdan
Published: February 2010

The 1H and 15Nα-enriched 1-phenylazo-3-X-2-naphthols, where X = COOH (I), X = COOCH3 (II), and X = CONHC6H5 (III), have been measured in various solvents. The values of 1J(15Nα, H) and σ(15N) indicate that in CDCl3, C6D6, CCl4, and CD3NO2 solutions the compounds I and III exist practically completely in their hydrazone forms. The hydrazone form is stabilized by the hydrogen bond of COOH or CONH protons to the C(2)=O group. The compound II represents an equilibrium mixture of azo and hydrazone forms, since it cannot form a similar hydrogen bond. Moreover, the 15N NMR spectra of compounds I-III have been measured in solid state by the CP/MAS technique. The results indicate the existence of two conformers differing by the conformation of COOCH3 group in compound II, which is supported by the 13C CP/MAS NMR spectrum of compound II.
Kinetics and mechanism of solvolysis of N-aryl sulfuric diamides
Authors: Kaválek Jaromír , Králíková Ulrika , Macháček Vladimír , Sedlák Miloš , Štěrba Vojeslav
Published: February 2010

The methanolysis and hydrolysis kinetics have been studied with the following sulfuric diamide derivatives: N-methyl-N-phenyl- (IIIa), N-methyl-N-(4-methoxycarbonylphenyl)- (IIIb), N-(4-methoxycarbonylphenyl)- (IIIc), N-methyl-N-(2-methoxycarbonylphenyl)- (IIId), N-(2-methoxycarbonylphenyl)- (IIIe), and N-methyl-N-(2,4-dibromophenyl)- (IIIf). The solvolyses of the neutral substrates IIIa and IIIb proceed by the addition-elimination mechanism. In the presence of the solvent lyate ions the solvolyses go by the E1cb mechanism. The solvolyses of the conjugated bases of compounds IIIa and IIIb are subject to general acid catalysis, the effects of the ring substituents being opposite to those in the addition-elimination mechanism. The solvolyses of compounds IIId and IIIf exhibit a distinct catalytic effect of neighbouring group; the reaction goes via a reactive intermediate, the transformation of the intermediate into the solvolysis product being subject to general acid and base catalysis.
The reaction of 2-methoxy-3-nitrothiophene with N-benzylmethylamine in methanol
Authors: Arnone Caterina , Consiglio Giovanni , Frenna Vincenzo , Spinelli Domenico
Published: February 2010

The kinetics of the title reaction has been studied in methanol as a function of amine and methoxide ion concentrations. The kinetic coefficients obtained point out that the reaction is catalysed by methoxide through a SB catalysis mechanism.
Enantioselective Diels-Alder reaction of (E)-1-trimethylsilyloxy-1,3-butadiene with chiral glyoxylates
Authors: Červinka Otakar , Svatoš Aleš , Trška Petr , Pech Pavel
Published: February 2010

Enantioselective Diels-Alder reaction of (E)-1-trimethylsilyloxy-1,3-butadiene (I) with chiral (-)-menthyl (II) and (-)-8-phenylmenthyl (III) glyoxylates in various solvents without or with catalysts was studied. The reactions gave a mixture of trans-and cis-isomers of (-)-menthyl (IV) and (-)-8-phenylmenthyl (V) 2-trimethylsilyloxy-5,6-dihydro-2H-pyran-6-carboxylates. The regioselectivity of the reaction was explained by quantum-chemical calculations, the enantioselectivity was determined using 13C NMR spectroscopy and the absolute configuration of the addition products was assigned on the basis of chemical correlation with (S)-(-)-dimethyl malate.
Beckmann rearrangement of (Z)- and (E)-oximes of 2-aryl-4,5,6,7-tetrahydro-6,6-dimethyl-2H-benzo[d][1,2,3]-triazol-4-ones and 4,5,6,7-tetrahydro-6,6-dimethylbenzo[c][1,2,5]oxadiazol-4-ones
Authors: Mitkidou Sophia , Stephanidou-Stephanatou Julia , Tsoleridis Constantinos A. , Alexandrou Nicholas E.
Published: February 2010

The synthesis and geometry of (Z)- and (E)-oximes, II and III, derivatives of tetrahydro-2H-benzo[d][1,2,3]triazoles and tetrahydrobenzo[c][1,2,5]oxadiazoles, was investigated. The possibility of structural assignments of II and III by Beckmann rearrangement was examined. Some CNDO/2 calculations were also carried out on the oximes II and III.
Explicit relationships for the terminal velocity of spherical particles
Authors: Hartman Miloslav , Veselý Václav , Svoboda Karel , Havlín Vladimír
Published: February 2010

The Turton-Levenspiel correlation for the drag coefficient of a sphere is employed to compare recently proposed explicit equations to predict the free-fall conditions. Predictions of four different expressions are explored over a wide range of Archimedes number.
29Si and 13C nmr spectra of trimethylsiloxy and hydroxy adamantanes reinvestigated at low concentration in deuteriochloroform solutions
Authors: Schraml Jan , Čermák Jan
Published: February 2010

29Si and 13C NMR chemical shifts are reported for mono- and bis(trimethylsiloxy)adamantanes as well as for mono- and dihydroxyadamantanes dissolved in deuteriochloroform. The chloroform induced changes in 29Si and 13C chemical shifts can be qualitatively accounted for by hydrogen-bonding considering basicity and solvent accessibility of oxygen atoms in the solute molecules. The steric effects observed on the 29Si shifts are not due to an interaction of the terminal hydrogen atoms of the trimethylsilyl groups but are due to proximity of two oxygen atoms on one cyclohexane ring of the adamantane skeleton.
N,N'-diphenylacetamidinium carboxylates
Authors: Krechl Jiří , Smrčková Svatava , Ludwig Miroslav , Kuthan Josef
Published: February 2010

Various N,N'-diphenylacetamidinium carboxylates were prepared and the nature of amidinium-carboxylate interactions was examined by 1H and 13C NMR spectra. Correlation between pKa of the respective acids and 1H NMR shifts in CHCl3 is described. The compounds due to their solubility and other physico-chemical properties represent valuable models of lactate dehydrogenase active site.
Preparation of three diastereoisomers of 2-(1-methyl-1-phenylethyl)-5-methylcyclohexan-1-ol from (R)-(+)-pulegone
Authors: Červinka Otakar , Svatoš Aleš , Masojídková Milena
Published: February 2010

New isolation of (1R,2S,5R)-(-)-2-(1-methyl-1-phenylethyl)-5-methylcyclohexan-1-ol ((-)-8-phenylmenthol, Ia), prepared from (R)-(+)-pulegone, is described. The method consists in the preparation of phenylcarbamate of Ia and its transesterification with ethanol. Further two diastereoisomers of (-)-8-phenylmenthol were isolated: the (1S,2R,5R)-isomer IIa and the (1R,2R,5R)-isomer IIIa. Compounds Ia, IIa and IIIa were converted into their respective glyoxylates Ic, IIc and IIIc.
Preparation of selectively protected derivatives of 21-nor-5-pregnene-3β,20-diol
Authors: Pouzar Vladimír , Sameš Dalibor , Havel Miroslav
Published: February 2010

The preparation of selectively protected derivatives of the title diol (III) is described. Derivatives with protected hydroxyl in position 3 (IV, V and VI) were obtained by p-toluenesulfonic acid-catalyzed reaction of etienic acid (I) with dihydropyran, ethyl vinyl ether and methyl vinyl ether, respectively, and subsequent hydride reduction. The protection of the free primary hydroxyl in these compounds and the subsequent removal of the acetal protecting group in position 3 represents a suitable approach to 20-protected derivatives. The relative rates of cleavage of the acetal protecting groups and reaction conditions are discussed.
Derivatives of tetrahydro-2H-pyridine from photorearranged cycloadducts of nitrile oxides
Authors: Fišera Lubor , Ondruš Vladimír , Timpe Hans-Joachim
Published: February 2010

1,3-Dipolar cycloaddition of methoxycarbonylnitrile, furannitrile and substituted benzene nitrile oxides (X = 4-CH3, 4-OCH3, 3-OCH3, 4-Cl, 3-Cl, 2,4-diCl, 4-F) to dimethyl 7-(diphenylmethylene)bicyclo[2.2.1]hept-2-ene-5,6-dicarboxylate (XII) led exclusively to exo cycloadducts IV, on irradiation with a low-pressure mercury lamp afforded the required 4-substituted derivatives of dimethyl 2,2-diphenyl-5-formyl-3-azabicyclo[4.3.0]nona-4,9-diene-7,8-dicarboxylate (XI) as sole products. Selectivity of the photorearrangement of isoxazolines IV to enaminoaldehydes XI is due to a stabilization of the biradical VII by the overlap of the radical-electron with π-electrons of the C=C double bond and by two benzene rings. Quantum yields of the photorearrangement, established from the deficit of the starting IV, were found to be greater than those for the analogous oxabicyclic derivatives XVI. The reaction mechanism is proposed and the dependence on various solvents is pointed out; this reaction sequence, viz. the 1,3-dipolar cycloaddition followed by a photochemical rearrangement provides a new method for obtaining derivatives of tetrahydro-2H-pyridine from the well available cyclopentadiene.
ESR study of the structure and bonding parameters in binary copper(II) complexes of some α-amino acids and dipeptides
Authors: Strašák Milan , Durcová Zlatica
Published: February 2010

Binary 1 : 1 copper(II)-amino acid and copper(II)-dipeptide complexes, [CuL] and [CuL]+ (H2L = +H3N-CHR-CO-NH-CHR'-COO-, HL' = +H3N-CHR-COO-), have been investigated in aqueous solution by means of ESR and electron absorption spectroscopy. Molecular orbital coefficients characteristic of the metal-ligand bonds have been derived for an effective D4h local symmetry. It is suggested that at the pH near to the physiological conditions both histidine and tryptophan coordinate as a tridentate ligand via O(carboxyl), N(heterocyclic ring) and N(amino) atoms. ESR investigation at room temperature and in frozen aqueous solutions, and visible spectral evidence suggest histamine-like coordination of histidine and tryptamine-like coordination of tryptophan in the quatorial plane of the binary complexes. Since proline contains the imino group, there is no ionizable amide-NH-proton when it is inserted in a peptide chain, hence the proline-nitrogen is unable to bind metal ions in peptides.
Study of porous cellulose beads as a dye-ligand matrix. Effect of protein admixtures and concentration of immobilized dye in the quantitative analysis of lactate dehydrogenase: Cibacron blue interaction
Authors: Mislovičová Danica , Gemeiner Peter , Ďurišová Viera
Published: February 2010

The effect of protein admixtures and concentration of immobilized dye on the interaction of lactate dehydrogenase (LDH) with Cibacron Blue-bead cellulose has been studied by means of zonal chromatography with Cibacron Blue-dextran T 10 as the mobile ligand. The influence of both variables on the values of dissociation constants of complexes immobilized dye-LDH (KI-L) and mobile dye-LDH (KM-L) can be summarized as follows: The values of KI-L remained practically constant and were found to be lower than those of KM-L. The differences found in KI-L and KM-L values should help to estimate the contribution of nonspecific interaction of the matrix to the total interaction between dye-ligand and the enzyme.
Synthesis and reactions of 5-acetyl-2-amino-3-cyano-4-(5-X-2-furyl)-6-methyl-4H-pyrans
Authors: Marchalín Štefan , Ilavský Dušan , Kováč Jaroslav , Bruncko Milan
Published: February 2010

Substituted 2-amino-4-(5-X-2-furyl)-4H-pyrans IIIa-IIIe have been prepared by a cyclization reaction of 5-X-2-furylmethylenepropanedinitriles IIa-IIe with 2,4-pentanedione. In reaction of 3-(5-X-2-furyl)-methylene-2,4-pentanediones Ia-Ie with propanedinitrile the formation of 4H-pyrans IIIa-IIIe is accompanied, depending on the catalyst type, by the formation of 5-X-2-furylmethylenepropanedinitriles IIa-IIe. 2-(4-Methylbenzylideneamino)-4H-pyran (V), 2-formylamino-4H-pyran (VI), and 3H, 5H-pyrano[2,3-d]pyrimidine-4-one (VII) have been synthesized by functional modifications of the amino group in 4H-pyran IIIa. The transformation of 4H-pyran ring into pyridine ring gives - from 4H-pyran IIIa - 5-acetyl-3-cyano-4-(2-furyl)-6-methyl-3,4-dihydro-2(1H)-pyridone (VIII) and 5-acetyl-2-amino-3-cyano-4-(2-furyl)-6-methylpyridine (IX). The structure of synthesized compounds III-IX has been proved by means of IR, UV, and NMR spectra.
The reaction of thioglycolic acid with α,β-unsaturated nitriles: A new route for the synthesis of thiazolo[3,2-a]pyridines
Authors: Elnagdi Mohamed Hilmy , Elmoghayar Mohamed Rifat Hamza , Elghandour Ahmed Hafez Hussein , Sadek Kamal Usef
Published: February 2010

The reaction of cinnamonitriles with thioglycolic acid in the presence of a basic catalyst affords thiazolo[3,2-a]pyridine derivatives.
Simple and efficient synthesis of 4H-3,1-benzoxazines from 2-bromomethylphenyl isocyanate and amines
Authors: Gonda Jozef , Barnikol Mariana
Published: February 2010

Reaction of 2-bromomethylphenyl isocyanate (II; prepared by radical bromination of 2-tolyl isocyanate with N-bromsuccinimide) with aliphatic and aromatic amines takes place on the NCO group under formation of stable N-alkyl(aryl)-N'-(2-bromomethylphenyl)ureas III. On treatment with sodium hydrogen carbonate in water or sodium hydride in N,N-dimethylformamide, the ureas III are cyclized to give 2-alkyl(aryl)amino-4H-3,1-benzoxazines IV in good yields. Reaction of isocyanate II with alcohols leads to alkyl 2-bromomethylphenyl carbamates. Structure of the synthesized compounds has been proven by spectral methods and elemental analysis.
9,10-Dihydroergopeptines modified in position 6
Authors: Beran Miloš , Černý Antonín , Kuchař Miroslav , Adamírová Hana , Holubek Jiří , Taimr Jan , Vachek Jaroslav , Frühaufová Maria , Řežábek Karel , Valchář Martin , Krejčí Ivan
Published: February 2010

9,10-Dihydroergopeptines modified in position 6 (VII-XXIII) were prepared from 9,10-dihydroergotamine (I) and 9,10-dihydroergocristine (II) which were converted via corresponding 6-demethyl-6-cyano compounds III and IV to 6-demethyl-9,10-dihydroergotamine (V) or 6-demethyl-9,10-dihydroergocristine (VI), respectively, which were then alkylated or acylated in position 6. Methylation of 6-demethyl-6-propyl compounds VIII and IX on N1 gave 1-methyl-6-demethyl-6-propyl-9,10-dihydroergotamine (XXIV) and 1-methyl-6-demethyl-6-propyl-9,10-dihydroergocristine (XXV). In the majority of the compounds their antinidation properties, affinity to α1 adrenergic receptors and D2 receptors of dopamine were studied, and in some of them the protective effect against adrenaline and noradrenaline and dopaminergic activity in vivo were also tested.
Isolation and partial characterization of boar proacrosin
Authors: Jonáková Věra , Vidimská Brigita , Urbanová Jana , Pavlík Manfred
Published: February 2010

Boar proacrosin was purified to apparent homogeneity by a three-step procedure: gel filtration on Sephadex G-50 medium, ion-exchange chromatography on CM-Cellulose 32, and reversed-phase high-performance liquid chromatography on a C4 column. The relative molecular mass (Mr) of the proacrosin estimated by gel filtration was about 70 000, whereas the results of an electrophoretic experiment on SDS-polyacrylamide gel with copolymerized casein under non-reducing conditions indicated an Mr of 55 000-60 000. The proacrosin reproducibly migrated on the gel as a double band. When purified, it remained stable at pH 8.0 for 30 min. The amino-acid composition of the homogeneous proacrosin was determined, the N-terminal amino-acid sequence being Arg-Asp-X-Ala-Thr-X-X-Gly-Pro-X-Gly-.
Can fluorosyl hydride be formed or even prepared?
Authors: Zahradník Rudolf , Hess B. Andes
Published: February 2010

HFO and HClO (fluorosyl and chlorosyl hydrides) and isomeric molecules HOF and HOCl (hypofluorous and hypochlorous acids) have been studied theoretically. On the basis of nonempiracal quantum chemical calculations (MP2, MP4 and CCD/6-311G**) geometry, energy and vibrational characteristics are analyzed and it is concluded that there is a poor chance to observe formation of HFO. Possibly, bombardment of HF in a solid matrix by 16O could lead at very low temperature to HFO.
Theory of metal ions accumulation by the synergistic adsorption at mercury electrodes
Authors: Mlakar Marina , Lovrić Milivoj , Branica Marko
Published: February 2010

The synergistic adsorptive accumulation of metal ions at the surface of mercury electrodes is described. The basic thermodynamic relationships between the ionic species involved in the synergistic adsorption are developed and analysed. The method is compared with the simple anion-induced adsorption. The synergistic adsorption of uranyl ions in the system salicylic acid-tributylphosphate is reported.
Potentiometric ion-pair formation titrations of N-alkyl-N-ethylpyrrolidinium cations using plastic membrane electrodes
Authors: Vytřas Karel , Čapoun Tomáš , Halámek Emil , Souček Jan , Štajerová Blanka
Published: February 2010

Cations of the homologous series of N-alkyl-N-ethylpyrrolidinium salts were determined with a good precision by a titration using sodium tetraphenylborate titrant and potentiometric indication with a simple PVC membrane coated-wire electrode. The value of the potentiometric titration break depended on the number of carbon atoms in the alkyl chain. To explain the role of the equilibria involved, the values of both the distribution ratios and the extraction constants as well as the solubility products of N-alkyl-N-ethylpyrrolidinium tetraphenylborates were determined. The value of the titration break could readily be correlated with the logarithmic values of the extraction parameters.
Determination of the structure of bis(propyldithiocarbamate)nickel(II)
Authors: Kameníček Jiří , Pastorek Richard , Březina František , Kratochvíl Bohumil , Trávníček Zdeněk
Published: February 2010

The crystal and molecular structure of the title compound (C8H16N2NiS4) was solved by the heavy atom method and the structure was refined anisotropically to a final R factor of R = 0.029 (wR = 0.037) for 715 observed reflections. The crystal is monoclinic, space group P21/c with a = 948.3(2), b = 776.9(2), c = 1 167.4(2) pm, β = 125.14(2)°, Z = 2. The molecule contains two four-membered NiSCS rings of approximately planar configuration with the Ni atom situated at a centre of symmetry. The molecules are arranged in chains along the c-axis of the unit cell.
Kinetics of methyl tert. butyl ether synthesis in gaseous phase
Authors: Hejtmánková Alena , Jeřábek Karel , Setínek Karel
Published: February 2010

Kinetics of methyl tert.butyl ether synthesis from methanol and isobutene was measured in gaseous phase at 85 °C and atmospheric pressure on macroreticular ion exchanger catalyst containing strongly acidic functional groups SO3H and on the same catalyst partially neutralized by sodium and iron ions. The form of the best Langmuir-Hinshelwood type kinetic equation suggests absorption of the reactants in the polymer mass causing ìswellingî of it and influencing the accessibility of active sites by the reactants. Neutralization of the catalyst by metal ions suppresses this effect.
Synthesis and reactions of 2-(2-arylvinyl) pyrimidines
Authors: El-Bahaie Said , Assy Mohamed G. , Kadry Azza
Published: February 2010

2-(2-Arylvinyl)-4-mercapto-5-acetylpyrimidines IIIa-IIId were synthesized by condensation of cinnamoyl isothiocyanates Ia-Id with 2-aminopent-2-ene-4-one II. The synthesis of 4-methylthio-, 4-(β-cyano)ethylthio- and 4-oxopyrimidines is also described. Compounds IV reacted with hydrazine hydrate to yield the corresponding pyrazolopyrimidine.
Synthesis and biological properties of vasopressin analogues containing 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid
Authors: Procházka Zdenko , Ancans Juris E. , Slaninová Jiřina , Machová Alena , Barth Tomislav , Lebl Michal
Published: February 2010

Solid phase synthesis methodology on a benzhydrylamine resin was used for the synthesis of three analogues of vasopressin with the non-coded amino acid, 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (Tic), in the position 2 ([Tic2, Lys8]VP (I)) and in the position 3 ([Tic3, Lys8]VP (II)). The analogue containing only one Tic in place of both aromatic residues was also isolated (des-Tyr2-[Tic3, Lys8]VP (III)). The biological activities of all analogues were negligible.
New fluorogenic substrates for the determination of post-proline endopeptidase activity
Authors: Tzougraki Chryssa , Kokotos George , Mašková Hana P. , Anzenbacherová Eva , Barth Tomislav
Published: February 2010

A new fluorogenic substrate for determination of the activity of post-proline endopeptidase (EC 3.4.21.26), Z-Cys(Bzl)-Pro-NH-Meq has been synthesized. Affinity of this substrate to the enzyme was significantly higher than that of the hitherto employed substrates. The Michaelis constant of the post-proline endopeptidase for Z-Cys(Bzl)-Pro-NH-Meq was at the optimum pH (7.0) 1.05 10-6 mol l-1. The concentration of dimethylsulfoxide used for the solubilization of Z-Cys(Bzl)-Pro-NH-Meq (<0.4%) was outside the limits of adverse influence of the organic solvent on the enzyme activity. The fluorogenic substrate Z-Gly-Pro-NH-Meq was also synthesized for comparison (Km = 10.35 10-6 mol l-1 at pH 7.0).
Generation of electronically excited states by means of methemoglobin and methemoglobin-haptoglobin complex
Authors: Hájková Hana , Pavlíček Zdeněk
Published: February 2010

It has been found that both human methemoglobin and its complex with human haptoglobin in their enzymatic action can generate products in electronically excited states. The time dependence has been measured of the chemiluminescence generated by both the haem proteins in their peroxidase as well as oxidase actions. The methemoglobin-haptoglobin complex exhibited, in its peroxidase action, a higher chemiluminescence as compared with methemoglobin alone. The chemiluminescence observed in the oxidase reaction was the same with both the haem proteins. The Stern-Volmer plots for quenching of chemiluminescence with indole and acrylamide have been constructed for both enzymatic reactions.
Conversion of bilirubin by transfer of electronic excitation energy generated in the presence of human methemoglobin
Authors: Pavlíček Zdeněk , Hájková Hana
Published: February 2010

The conversion of bilirubin into colourless products has been induced by transfer of electronic excitation energy and followed spectrophotometrically. The triplet excitation energy was generated by oxidation of 2-methylpropanal with oxygen in solution under catalytic action of human methemoglobin. A slower kinetics of transformation of bilirubin via this "photochemical reaction without light" has been observed for the bilirubin bound to human albumin as compared with the bilirubin alone.
Anion effect on alkali ion-crown complex formation in a moderately concentrated solutions: A sensitive probe of hidden interionic interactions operating in dissociating protic solvents
Authors: Závada Jiří , Pechanec Václav , Kocián Oldřich
Published: February 2010

A powerful anion effect destabilizing alkali ion-crown complex formation has been found to operate in moderately concentrated protic (H2O, CH3OH, C2H5OH) solution, following the order HO- > AcO- > Cl- > Br- > NO3- > I- > NCS-. Evidence is provided that the observed effect does not originate from ion-pairing. A simple explanation is provided in terms of concordant hydrogen bond bridges of exalted stability between the gegenions, M+···OR-H···(OR-H)n···OR-H···A-. It is proposed that encapsulation of alkali ion by the macrocyclic ligand leads to a dissipation of the cation charge density destroying its ability to participate in the hydrogen bond bridge. An opposition against the alkali ion-crown complex formation arises accordingly in the solution in dependence on strength of the hydrogen bridge; for a given cation, the hydrogen bond strength increases with increasing anion charge density from NCS- to HO-(RO-). It is pointed out, at the same time, that the observed anion effect does not correlate with the known values of activity coefficients of the individual alkali salts which are almost insensitive to anion variation under the investigated conditions. As a resolution of the apparent paradoxon it is proposed that, in absence of the macrocyclic ligand, the stabilizing (concordant) bonding between the gegenions is nearly balanced by a destabilizing (discordant) hydrogen bonding between the ions of same charge (co-ions). Intrinsic differences among the individual salts are thus submerged in protic solvents and become apparent only when the concordant bonding is suppressed in the alkali ion-crown complex formation.
Kinetics of reaction of 1,2-diaminobenzene with phenylglyoxal
Authors: Klicnar Jiří , Mindl Jaromír , Štěrba Vojeslav
Published: February 2010

The cyclization reaction kinetics of phenylglyoxal monohydrate with 1,2-diaminobenzene have been studied in formate, acetate, and phosphate buffers. At high pH values and low buffer concentrations the rate-limiting step consists in the protonation of the intermediate formed by addition of the first amino group to aldehydic group of phenylglyoxal. With increasing concentrations of formate and acetate buffers the rate-limiting step shifts to the formation of the intermediate. In phosphate buffers the catalysis by the basic buffer component makes itself felt, too. At higher concentrations of 1,2-diaminobenzene, the dehydration of phenylglyoxal monohydrate gradually becomes the rate-limiting step.
Synthesis of optically active 1-(2-furyl)-3-pentanol. A simple route to (2S, 5R/S)-chalcogran
Authors: Körblová Eva , Koutek Bohumír , Šaman David , Svatoš Aleš , Maloň Petr , Romaňuk Miroslav
Published: February 2010

Enantioselective synthesis of the title alcohol VI is reported, which utilizes either pig pancreatic lipase mediated transesterification or a reduction with baker's yeast at the key steps. The transesterification of VI gives (S)-(+)-VI (e.e. 80%) or (R)-(-)-V (e.e. 50%), while the reduction of the corresponding α,β-unsaturated ketone IV affords (R)-(-)-VI (e.e. 30%). These intermediates allowed to prepare a mixture of chalcogran I diastereoisomers containing 54% of the biologically active (2S, 5R) isomer.
Potential neuroleptics of the orthopramide series; synthesis of heterocyclic 5-amino-2-methoxybenzamides and of some related compounds
Authors: Valenta Vladimír , Holubek Jiří , Svátek Emil , Matoušová Oluše , Metyšová Jiřina , Protiva Miroslav
Published: February 2010

2-Methoxy-5-nitrobenzoyl chloride was reacted with 2-(aminomethyl)-1-ethylpyrrolidine, 3-amino-1-ethylpiperidine, 4-amino-1-benzylpiperidine, 1-benzylpiperazine, and 1-amino-4-benzylpiperazine and gave the N-substituted 2-methoxy-5-nitrobenzamides VIa-VIe. Their reduction with hydrazine hydrate and Raney nickel in ethanol afforded the corresponding 5-amino-2-methoxybenzamides VIIa-VIIe. The amino amides VIIb and VIIc were transformed to methylamino compounds XIb and XIc via the 4-toluenesulfonamides VIIIb and VIIIc and the N-methyl-4-toluenesulfonamides Xb and Xc. The N-(1-benzyl-4-piperidinyl)amides VIc, VIIc and XIc were found to be mild neuroleptics having antiapomorphine, some cataleptic and some ataxic activity.
One step introduction of the activated carboxyl groups with long aliphatic arm onto hydroxyl groups containing polymers
Authors: Arnold Luboš , Smrt Jiří
Published: February 2010

Bis-N-hydroxysuccinimide ester of 1,10-decanediol bis-succinate (Ia) reacts with hydroxyl groups bearing polymers (Spheron, cellulose, Sephacryl) affording activated carboxyl group containing derivatives IIa. Analogous 4-nitrophenyl group bearing Spheron derivative IIb was prepared starting from bis-4-nitrophenyl ester of 1,10-decanediol bis-succinate (Ib). 3'-O-(4,4'-Dimethoxytriphenylmethyl)-2'-deoxythymidine 5'-(6-amino-1-hexyl)-phosphate (V) was developed as reagent to determine the extent of activated carboxyl groups. Attachment ranging from 3.1-7.3 μmol/g was achieved.
Equations for calculating the constants of enzyme inhibition/activation by n inhibitors/activators
Authors: Krupyanko Vladimír I.
Published: February 2010

Based on the method of vector representation of enzyme reactions in three-dimensional K'mV' coordinates, equations for calculating the constants of enzyme inhibition Ki(n) and activation Ka(n) by two or more inhibitors/activators were deduced. Inhibition of calf alkaline phosphatase by anions of molybdic (MoO42-) and tungstic (WO42-) acid was studied. The constants of enzyme inhibition by each of these anions and by their mixture in the same concentration were determined. The value of the phosphatase inhibition constant obtained experimentally was compared with that calculated using the appropriate equation. The prospects of using the equations obtained to analyze the kinetics of enzyme inhibition/activation by two or more simultaneous inhibitors/activators and to assess the contribution of each of these compounds are discussed.
Modification of arginine residues of pea lactate dehydrogenase by phenylglyoxal
Authors: Barthová Jana , Kunová Jana , Leblová Sylva
Published: February 2010

Electrophoretically homogeneous lactate dehydrogenase was isolated from germinating pea seedlings by chromatography on AMP-Sepharose 4B. The amino acid composition of the enzyme was determined as well as the values of the Michaelis constants for four substrates and of the dissociation constants for the binary enzyme-coenzyme complexes. The treatment of the enzyme with phenylglyoxal resulted in the modification of nine arginine residues in its subunit. The modification was paralleled by a complete inactivation of the enzyme. The role of the arginine residues in the active center probably involves the binding of substrates, lactate and pyruvate, to the apoenzyme by an ionic bond.
Evidence for the role of carboxyl groups in activity of endopolygalacturonase of Aspergillus niger. Chemical modification by carbodiimide reagent
Authors: Rexová-Benková Lubomíra
Published: February 2010

Endopolygalacturonase (E.C. 3.2.1.15) of Aspergillus niger was modified with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and glycine ethyl ester. The modification resulted in total irreversible inactivation of the enzyme and derivatization of carboxyl acid residues and tyrosine residues. The treatment of the modified enzyme with hydroxylamine led to a restoration of modified tyrosine residues but not to reactivation of the enzyme. The inactivation with carbodiimide was pH dependent, the rate of inactivation increased with decreasing pH. Tri(D-galactosiduronic acid), a competitive inhibitor, or crosslinked pectic acid protected the enzyme against the inactivation. In bioaffinity chromatography of partially inactivated endopolygalacturonase, all residual enzyme activity was retained on the adsorbent while all inactive fraction passed without retardation through the column. On the basis of these results, as well as proximity of the rate constants for enzyme inactivation and the carboxyl group modification it is suggested that the loss of endopolygalacturonase activity is due to the modification of carboxylic acid residues and that at least one is essential for enzyme activity.
MNDO and AM1 study of molecular geometries in excited states
Authors: Ertl Peter
Published: February 2010

Geometries of the singlet excited states of series of organic molecules have been calculated using MNDO and AM1 semiempirical methods with limited configuration interaction. Changes in molecular geometries after excitation are reproduced reasonably well, with AM1 being superior to MNDO, which in some cases fails. Molecules having biradical-like character in excited state are described better than classical ones.
Statistical study of a large structural file based on the Mendeleev table
Authors: Petitjean Michel , Dubois Jacques Emile
Published: February 2010

The atom or element content of a large structural file is considered through relations between the occurrences of the elements and their geometric distribution obtained by correspondence analysis over the Mendeleev periodic table, which is considered as a rectangular (7 x 32) contingency table. The potential of various geometric tools is explored with different CAS files.
Crystal and molecular structure of 2-dimethylaminomethyl-3'-hydroxydiphenyl sulphide maleate
Authors: Schneider Bohdan , Hašek Jindřich , Ječný Jiří
Published: February 2010

The crystal and molecular structure of the title compound, C19H21NO5S, M = 375.44, was solved by X-ray structure analysis using diffractometer intensity measurement with CuKα radiation. The space group is P1, with lattice parameters a = 555.7(3), b = 1 697.0(8), c = 1 035.4(4) pm, α = 106.77(4)°, β = 98.19(4)°, γ = 90.64(4)°, V = 923.9(8) . 106 pm3, Z = 2, ρcalc = 1.349 g/cm3, ρm = 1.32 g/cm3. Anisotropic refinement of all nonhydrogen and isotropic refinement of eight hydrogen atoms converged to R = 0.056 and wR = 0.114 for 2 481 observed reflections. Hydrogen bonds O18-H181···O25 and N9-H91···O24i join neighbouring diphenyl sulphide and maleate molecules to linear chains. The parallel chains interact through van der Waals contacts only. Molecules of maleic acid are nearly planar keeping π-electron delocalization. An angle between phenyl rings of the diphenyl sulphide molecule is 80.9(1)° and torsion angles around S-C bonds are 23.2(3)° and 73.6(3)°.
Synthesis of alkenes by Wittig reaction using lithium 1,3-diaminopropane as a base
Authors: Streinz Ludvík , Šaman David , Konečný Karel , Romaňuk Miroslav
Published: February 2010

It has been found that the lithium 1,3-diaminopropane (X) can be used for generation of non-stabilized ylides from alkyltriphenylphosphonium salts. These ylides with aldehydes afford olefins in moderate yield with high Z-stereoselectivity. The reaction conditions were studied.
Sesquiterpenic lactones of the Inula caspica BLUME species
Authors: Adekenov Sergazy M. , Buděšínský Miloš , Abdikalikov Metram A. , Turdybekov Coblandy M. , Šaman David , Błoszyk Ełżbieta , Drożdż Bohdan , Holub Miroslav
Published: February 2010

From Inula caspica BLUME (Compositae) were isolated 3β-hydroxy-2α-senecioyloxyisoalantolactone (I), whose structure was confirmed by X-ray diffraction and completed by determination of its absolute configuration, and britannin (II) whose relative configuration was determined by X-ray diffraction and absolute configuration by CD spectroscopy.