共查询到20条相似文献,搜索用时 31 毫秒
1.
A monosialoganglioside, IV 3-NeuNAcLcOse 4Cer, has recently been detected in colorectal carcinoma cells, small cell lung carcinoma cells, embryonal carcinoma cells and in human brain extracts. We report here the presence of a CMP-sialic: LcOse 4Cer sialyl transferase activity in subcellular membrane fractions of the human colorectal carcinoma, SW1116, which recognizes the non-reducing terminal galactosyl moiety of lactotetraosylceramide. A convenient method for structural analysis of picomolar quantities of the radioactive enzymatic product(s) using bacterial endoglycoceramidase, sialidase and a viral sialidase is presented. 相似文献
2.
A human strain of influenza virus (A, H1N1) was shown to bind in an unexpected way to leukocyte and other gangliosides when compared with avian virus (A, H4N6) as assayed on TLC plates. The human strain bound only to species with about 10 or more sugars, while the avian strain bound to a wide range of gangliosides including the 5-sugar gangliosides. By use of specific lectins, antibodies, and FAB and MALDI-TOF mass spectrometry an attempt was done to preliminary identify the sequences of leukocyte gangliosides recognized by the human strain. The virus binding pattern did not follow binding by VIM-2 monoclonal antibody and was not identical with binding by anti-sialyl Lewis x antibody. There was no binding by the virus of linear NeuAcalpha3- or NeuAcalpha6-containing gangliosides with up to seven monosaccharides per mol of ceramide. Active species were minor NeuAcalpha6-containing molecules with probably repeated HexHexNAc units and fucose branches. This investigation demonstrates marked distinctions in the recognition of gangliosides between avian and human influenza viruses. Our data emphasize the importance of structural factors associated with more distant parts of the binding epitope and the complexity of carbohydrate recognition by human influenza viruses. 相似文献
3.
Sialyl-linkage specificity of sialidases of the human influenza A virus
strains, A/Aichi/2/68 (H3N2) and A/PR/8/34 (H1N1) were studied using
natural and synthetic gangliosides. The sialidase of the A/Aichi/2/68
strain hydrolyzed the terminal Neu5Acalpha2-3Gal sequence but not the
Neu5Acalpha2-3 linkage on the inner Gal of GM1a, which is a ganglioside
that has the gangliotetraose chain (Galbeta1-3GalNAcbeta1-4-
(Neu5Acalpha2-3)Galbeta1++ +-4Glcbeta1-Cer). The sialidase hydrolyzed the
Neu5Ac on the inner Gal of GM2, which had a shorter gangliotriose chain.
GM4, which had the shortest chain (Neu5Acalpha2-3Galbeta1-Cer) of the
gangliosides, had a lower substrate specificity. The N1 and N2 sialidase
subtypes of the human influenza A virus had no significant variation in
their substrate specificity for the gangliosides. Analysis of 11 synthetic
gangliosides, which contained various ceramide or sialic acid moieties,
demonstrated that A/Aichi/2/68 (H3N2) sialidase recognized the ceramide and
sialic acid moiety and the length and structure of the sialyl sugar chain.
相似文献
4.
Eighteen gangliosides were isolated from dogfish ( Squalus acanthias) brain, and their structures and compositions were determined by methylation analysis, enzymatic hydrolysis and partial hydrolysis with mild acid. Tetra- and pentasialogangliosides were also analysed by liquid secondary ion mass spectrometry. The dogfish brain gangliosides were characterized by a variety of molecular species. The most abundant ganglioside was GM2 (22.8% of the total sialic acid content), followed by GQ1c (16.0%), GP1c (13.4%), and GD2 (12.5%). The abundance of gangliosides containing a gangliotriaose core (GM2 and GD2), and c-series polysialogangliosides (GQ1c and GP1c) was a prominent feature of dogfish brain, differing from the brain gangliosides of teleosts and other vertebrates. A battery of trisialogangliosides was also found. A ganglioside which had an a- and -series hybrid-structure (IV 3NeuAc,III 6NeuAc,II 3NeuAc-Gg 4Cer) comprised 1.4% of the total. The major fatty acids comprised 16:0, 18:0, 18:1, 22:1 and 24:1. The gangliosides with a gangliotriaose core predominantly contained 22:1. Sphinganine and 4-sphingenine comprised the long-chain bases. 相似文献
5.
A number of N, N′-bis(4-substituted phenyl)-1,7-diaza-12-crown-4 and N, N′-bis(4-substituted phenyl)-1, 10-diaza-18-crown-6 (where the substituents are OCH 3, CH 3, H, Cl, respectively) have been prepared by cyclization reaction of a ditosylate with the appropriately substituted diol. These new macrocyclic ligands have been characterized by means of elemental analysis, IR, 1H NMR and MS spectra. The crystal structures of N, N′-bis(4-chlorophenyl)-1,10-diaza-18-crown-6 (21) and its complex with barium thiocyanate Ba(SCN) 2 (22) have been determined by single crystal X-ray diffraction. The crystallographic data are as follows: 21: C 24H 32Cl 2N 2O 4, orthorhombic, P2 12 12 1, A=4.852(1), B=11.989(2), C=41.231(8) Å, V=2398.7(8) Å 3, Z=4; 22: C 26H 32Cl 2N 4O 4S 2Ba, monoclinic, P2 1/ c, A=8.801(2), B=11.653(9), C=15.756(6) Å, ß=105.96(3)°, V=1553.7(14) Å 3, Z=2. In the complex, the Ba atom is eight-coordinate (O(1), O(2), O(1)′, O(2)′, N(1), N(1)′, N(21), N(21)′) to form a distorted D6h geometry with the Ba atom at the center of crystallographic symmetry. 相似文献
6.
Abstract: Pineal arylalkylamine N -acetyltransferase ( N -acetyltransferase) controls large daily changes in melatonin production. It is generally thought that the activity of this enzyme is controlled by norepinephrine acting exclusively via elevation of cyclic AMP. However, norepinephrine also elevates pineal intracellular Ca 2+ concentration ([Ca 2+] i), and it is not known whether Ca 2+ is involved in regulating N -acetyltransferase activity other than through its established role in cyclic AMP production. In this study, the issue of whether Ca 2+ enhances the effects of cyclic AMP on N -acetyltransferase activity was investigated. The effects of cyclic AMP protagonists (isobutylmethylxanthine, N 6, 2'- O -dibutyryladenosine 3',5'-cyclic monophosphate, 8-bromoadenosine 3',5'-cyclic monophosphate, and adenosine 3',5'-cyclic monophosphothioate, Sp-diastereomer) were examined in combination with [Ca 2+] i protagonists (A23187, ionomycin, and phenylephrine). All [Ca 2+] i protagonists potentiated the effects of cyclic AMP protagonists. For example, ionomycin potentiated the effects of low concentrations of 8-bromoadenosine 3',5'-cyclic monophosphate, and A23187 potentiated the effects of isobutylmethylxanthine without altering cyclic AMP accumulation. These findings indicate that Ca 2+ and cyclic AMP probably act physiologically in a coordinated manner to stimulate N -acetyltransferase activity; these second messengers could act directly at one or more sites or through indirect actions mediated by kinases. 相似文献
7.
Kinetic studies of the addition of a wide range of tertiary phosphines and phosphites to the tropylium ring of the cation [Cr(CO) 3(η 7-C 7H 7] + (1) reveal the two-term raw, kobs = k1[PR 3] + k−1. This is consistent with the reversible equilibrium process (i) which is also confirmed from IR and 1H NMR studies. In the case of the highly basic nucleophiles PBu 3n and PEt 2Ph, the rate is dominated by the k1 term and the equilibrium lies far to the right. The first-order rate constants k1, for addition to the tropylium ring decrease markedly down the series PBu 3n>PEt 2Ph>P(4-MeOC 6H 4) 3>P(4-MeC 6H 4) 3>P(C 6H 11 3>PPh 2(4-MeC 6H 4)>PPh 3>P(2-CNC 2H 4) 3>P(OBu n) 3 (overall variation 10 4). This reactivity order parallels the decreasing electron availability at the phosphorus centres, as confirmed by the linear correlation between log k1 and the Tolman Σ χ values for the nucleophiles. Excellent Hammett and Brønsted correlations are also observed for ring addition by a range of P(4-XC 6H 4) 3 nucleophiles. The Brønsted slope, , of 0.7 conirms the major importance of basicity in determining nucleophilicity towards cation 1. Kinetic studies of the related additions of PBu 3n to the cations [M(CO) 3(η 7-C 7H 7] + (M = Mo, W) reveal the rate law, Rate = k1[M][PBu 3n, and show only a small dependence of k1 on the nature of metal (Cr>WMo; 2:1.1:1). These data, together with the associated activation parameters, support a mechanism involving direct addition ( k1) of the phosphorus nucleophiles to the tropylium ring, and are inconsistent with initial rate-determining attack at the metal centre. 相似文献
8.
A mouse monoclonal antibody, VIM-2, specific for human blood cells of myelomonocytic lineage, was found to bind to a series of minor gangliosides isolated from the cells of patients with chronic myelogenous leukemia (Uemura, K., Macher, B.A., DeGregorio, M., Scudder, P., Buehler, J., Knapp, W., and Feizi, T. (1985) Biochim. Biophys. Acta 846, 26-36). TLC immunostaining studies with the VIM-2 antibody of gangliosides from normal human neutrophils, acute myeloid leukemia, and chronic myelogenous leukemia cells showed that the total amount and the ratio of the VIM-2 gangliosides varies among these different myeloid cells and appears to be related to the level of cellular differentiation. Purification of these gangliosides from chronic myelogenous leukemia cells was aided by a sensitive enzyme-linked immunosorbent assay procedure used in conjunction with high performance liquid chromatography. Structures for two of the immunoreactive gangliosides (a ceramide decasaccharide, VIII3NeuAcV3-Fuc-nLc8Cer and a ceramide dodecasaccharide X3-NeuAcVII3Fuc-nLc10Cer) are proposed from negative ion fast atom bombardment mass spectrometry of the native gangliosides, methylation analysis, and the combined use of glycosidase treatment and TLC immunostaining with carbohydrate sequence specific antibodies. The VIM-2 antigen was thus characterized as involving the sialofucooligosaccharide sequence. 相似文献
9.
Abstract: Several gangliosides, especially G D3 (disialosyllactosyl ceramide) in the presence of another lipid (lecithin) were found to enhance the binding of serotonin to serotonin binding protein (SBP) severalfold. In our conditions, this enhancement was linear to a concentration of 2.7 × 10 −6I G D3 and a three- to fivefold increase in binding capacity of SBP was obtained with 8.8 × 10 −6 M. The addition of this ganglioside led to an increase of serotonin binding sites, but not to an increase in the affinity of SBP to serotonin. Optimal binding capacity was found with a ratio of lecithin to ganglioside of 6: 1 (w/w). No binding was found in the absence of either SBP or Fe 2+ (binding of serotonin to SBP is dependent on Fe 2+). Other glycosphingolipids (sulfatide, G D1a, G D1b, G M1) showed lesser effects at low concentration, whereas asialo-G M1, cytolipin H, galactocerebroside and G M3 had insignificant effects. Since earlier studies suggested a storage role for serotonin binding protein, the interaction of gangliosides with this protein may regulate the concentration of the biogenic amine in the synapse. 相似文献
10.
1. 1.|The influence of temperature changes on Ca2+-binding to brain ganglioside mixtures of different polarity, to single gangliosides (GM1, GD1a, GT1b) and to their deceramide was investigated potentiometrically by means of ion-selective electrodes. 2. 2.|Following cooling (3.5°C/min.) from 37 to 13°C the Ca2+-binding to gangliosides, except GM1, was increased (7–30%). 3. 3.|Subsequent rewarming from 13 to 37°C resulted in up to 100% release of previously-bound Ca2+. 4. 4.|When comparing the maximal absolute binding difference of Ca2+ to gangliosides during temperature changes a decrease of these differences could be stated which corresponds to an increase in the polarity of the gangliosides. 5. 5.|From these experiments it is concluded that a higher polarity of neuronal gangliosides is responsible for a lower thermal sensitivity of Ca2+-binding to these compounds. This may be involved in the process of thermal adaptation of ectothermic vertebrates.
Author Keywords: Ganglioside—Ca2+ complex; temperature; potentiometry; Gallus domesticus; Salmo gairdneri; brain 相似文献
11.
Both prostaglandins (PGs) and nitric oxide (NO) have cytoprotective and hyperemic effects in the stomach. However, the effect of NO on PG synthesis in gastric mucosal cells is unclear. We examined whether sodium nitroprusside (SNP), a releaser of NO, stimulates PG synthesis in cultured rabbit gastric mucus-producing cells. These cells did not release NO themselves. Co-incubation with SNP (2 × 10 −4, 5 × 10 −4, 10 −3 M) increased PGE 2 synthesis, and SNP (10 −3 M) increased PGI 2 synthesis in these cells. Hemoglobin, a scavenger of NO, (10 −5 M) eliminated the increase in PGE 2 synthesis by SNP, but methylene blue, an inhibitor of soluble guanylate cyclase, (5 × 10 −5 M) did not affect the increase in PGE 2 synthesis by SNP. 8-bromo guanosine 3′ : 5′-cyclic monophosphate (8-bromo cGMP), a cGMP analogue, (10 −6, 10 −5, 10 −4, 10 −3 M) did not affect PGE 2 synthesis. These findings suggest that NO increased PGE 2 and PGI 2 synthesis via a cGMP-independent pathway in cultured rabbit gastric cells. 相似文献
12.
The synthesis of the tetradentate pendant arm macrocycles 1,4,7-triazacyclononane- N-acetate (L 1) and N-(2-hydroxybenzyl)-1,4,7-triazacyclononane (HL 2) and their coordination chemistry with vanadium(IV) and (V) are reported. The following mononuclear species have been prepared and characterized by UV-Vis, IR spectroscopy: [L 1V IVO(NCS)] (1), [L 1VO 2]·H 2O (2), [L 2VO(NCS)] (3), [L 2VO(NCS)]Cl (4), and [L 2VO 2] (5). In addition, the dinuclear, mixed valent complexes [L 21V 2O 3]Br (6), [L 22V 2O 3](ClO 4)·0.5acetone (7), and the homovalent complex [L 22V 2O 3](ClO 4) 2 (8) have been synthesized. Complexes 2, 3, 6 and 7 have been characterized by single crystal X-ray crystallography. Crystal data: 2, space group P2 1c, a=9.944(4), b=6.701(3), c=18.207(8)Å, β=102.88(3)°, V=1182.7 Å 3, Z=4, Dcalc=1.51 g cm −3, R=0.049 based on 4760 reflections; 3, space group Pbca, A=11.003(6), b=14.295(7), C=20.21(1) Å, V=3178.8 Å 3, Z=8, Dcalc=1,50 g cm −3, R=0.057 based on 1049 reflections; 6, space Pbcn, a=12.922(3), B=13.852(3), C=12.739(3) Å, V=2280.3 Å 3, Z=4, Dcalc=1,75 g cm −3, R=0.047 based on 1172 reflections; 7, space group C2/ c, A=23.553(9), B=13.497(5), C=20.951(8) Å, β=90.03(3)°, V=6660.2 Å 3, Z=8, Dcalc=1.49 g cm −3, R=0.053 based on 3698 reflections. Complexes 6 and 7 are mixed valent V(IV)/(V) complexes containing the [OV---O---VO] 3+ core. In the solid state 6 belongs to class III (delocalized) and 7 to class I (localized) according to the Robin and Day classification of mixed valent compounds. A rationale for these differing electronic structures is given. 相似文献
13.
Abstract— The pathway of biosynthesis of N -acetylgalactosamine-containing gangliosides in mouse neuroblastoma has been studied using NB41A cells grown in monolayer tissue culture. Cell-free enzyme preparations catalyzed the transfer of NeuNAc from CMP-NeuNAc to lactosylceramide (GL-2a), to form G M3. Asialo-G M2 was neither an acceptor nor a competitive inhibitor of the sialyltransferase (CMP-NeuNAc: GL-2a N-acetylneuraminyltransferase, EC 2.4.99.-) under a variety of experimental conditions. Enzyme preparations also contained an N -acetylgalactosaminyltransferase (UDP-GalNAc. G M3 N -acetylgalactosaminyltransferase, EC 2.4.1.-) which catalyzed the conversion of G M3 to G M2. No significant transfer of N -acetylgalactosamine to GL-2a could be demonstrated. The results of the glycosyltransferase assays support the concept that the first NeuNAc of brain gangliosides is introduced into GL-2a. The present data suggests that the occurrence of asialo-G M2 in NB41A cells under some culture conditions is a consequence of the catabolism of higher gangliosides. 相似文献
14.
Syntheses and C-H bond activation reactions of the novel electrophilic Pt II complexes [(tmeda)Pt(CH 3)(OEt 2)][BAr 1], [(tmeda)Pt(CH 3)(THF)][BAr f], and [(tmeda)Pt(CH 3)(NC 5F 5)][BAr f] are described {[BAr f] − = [(3,5-C 6H 3(CF 3) 2) 4B] −} (tmeda is N,N,N′,N′-tetramethylethylenediamine), [(tmeda)Pt(CH 3)(OEt 2)][BAr f] and [(tmeda)Pt(CH 3)(THF)][BAr f] are unstable at room temperature, yielding methane and the Fischer carbene Pt II hydrides, [(tmeda)Pt(=C(CH 3)(OCH 2CH 3))(H)][BAr f] and . The methane liberated from [(tmeda)Pt(CH 3)(OEt 2- d10)][BAr f] consists of an isotopomeric mixture, (CH 4, CH 3D, CH 2D 2 and CHD 3), indicating a multiple H/D exchange reaction following the C-D activation and prior to methane loss. [(tmeda)Pt(CH 3)(THF- d8)][BAr] liberates CH 4 and CH 3D. Methane- 13C, cyclohexane, toluene, and benzene react with [(tmeda)Pt(CH 3)(NC 5F 5)][BAr f] to yield methane and new organoplatinum complexes. Deuterated alkanes and arenes react with [(tmeda)Pt(CH 3)(NC 5F 5] [BAr f] to give a mixture of methane isotopomers. The relevance of these results to the oxidation of alkanes by aqueous platinum complexes is discussed. 相似文献
15.
Rapid reactions occur between [Os VI(tpy)(Cl) 2(N)]X (X = PF 6−, Cl −, tpy = 2,2′:6′,2″-terpyridine) and aryl or alkyl phosphi nes (PPh 3, PPh 2Me, PPhMe 2, PMe 3 and PEt 3) in CH 2Cl 2 or CH 3CN to give [Os IV(tpy)(Cl) 2(NPPh 3)] + and its analogs. The reaction between trans-[Os VI(tpy)(Cl) 2(N)] + and PPh 3 in CH 3CN occurs with a 1:1 stoichiometry and a rate law first order in both PPh 3 and Os VI with k(CH 3CN, 25°C) = 1.36 ± 0.08 × 10 4 M − s −1. The products are best formulated as paramagnetic d 4 phosphoraniminato complexes of Os IV based on a room temperature magnetic moment of 1.8 μ B for trans-[Os IV(tpy)(Cl) 2(NPPh 3)](PF 6), contact shifted 1H NMR spectra and UV-Vis and near-IR spectra. In the crystal structures of trans-[Os IV(tpy)(Cl) 2( NPPh 3)](PF 6)·CH 3CN (monoclinic, P2 1/ n with a = 13.384(5) Å, b = 15.222(7) Å, c = 17.717(6) Å, β = 103.10(3)°, V = 3516(2) Å 3, Z = 4, Rw = 3.40, Rw = 3.50) and cis-[Os IV(tpy)(Cl) 2(NPPh 2Me)]-(PF 6)·CH 3CN (monoclinic, P2 1/ c, with a = 10.6348(2) Å, b = 15.146(9) ÅA, c = 20.876(6) Å, β = 97.47(1)°, V = 3334(2) Å 3, Z = 4, R = 4.00, Rw = 4.90), the long Os-N(P) bond lengths (2.093(5) and 2.061(6) Å), acute Os-N-P angles (132.4(3) and 132.2(4)°), and absence of a significant structural trans effect rule out significant Os-N multiple bonding. From cyclic voltammetric measurements, chemically reversible Os V/IV and Os IV/III couples occur for trans-[Os IV(tpy)(Cl) 2(NPPh 3)](PF 6) in CH 3CN at +0.92 V (Os V/IV) and −0.27 V (Os IV/III) versus SSCE. Chemical or electrochemical reduction of trans-[Os IV(tpy)(Cl) 2(NPPh 3)](PF 6) gives isolable trans-Os III(tpy)(Cl) 2(NPPh 3). One-electron oxidation to Os V followed by intermolecular disproportionation and PPh 3 group transfer gives [Os VI(tpy)Cl 2(N)] +, [OS III(tpy)(Cl) 2(CH 3CN)] + and [Ph 3=N=PPh 3] + (PPN +). trans-[Os IV(tpy)(Cl) 2(NPPh 3)](PF 6) undergoes reaction with a second phosphine under reflux to give PPN + derivatives and Os II(tpy)(Cl) 2(CH 3CN) in CH 3CN or Os II(tpy)(Cl) 2(PR 3) in CH 2Cl 2. This demonstrates that the Os VI nitrido complex can undergo a net four-electron change by a combination of atom and group transfers. 相似文献
16.
A cryptically I-active sialylglycoprotein (glycoprotein 2) isolated from bovine erythrocyte membranes as Sendai virus receptor (Suzuki, Y., Suzuki, T. and Matsumoto, M. (1983) J. Biochem. 93, 1621-1633) contains N-glycolylneuraminic acid (NeuGc) as its predominate sialic acid and exhibits poor receptor activity for a variety of influenza viruses. Enzymatic modification of asialoglycoprotein-2 to contain N-acetylneuraminic acid (NeuAc) in the NeuAc alpha 2-3Gal and NeuAc alpha 2-6Gal sequences using specific sialyltransferase resulted in the appearance of receptor activity toward human influenza viruses A and B. The biological responsiveness chicken erythrocytes treated with sialidase and then reconstituted with derivatized glycoprotein 2 showed considerable recovery to influenza virus hemagglutinin-mediated agglutination, low-pH fusion and hemolysis. Specific hemagglutination inhibition activity of derivatized glycoprotein 2 was 5-16-times higher than that of human glycophorin. A/PR/8/34 (H1N1) virus preferentially recognized derivatized glycoprotein 2 containing NeuAc alpha 2-3Gal sequence over that containing NeuAc alpha 2-6Gal while the specificity of A/Aichi/2/68 (H3N2) for the sialyl linkages was reversed. B/Lee virus recognized both sequences almost equally. The biological responsiveness to the viruses of the erythrocytes labeled with the derivatized glycoprotein 2 containing NeuGc was considerably lower than that of derivatized glycoprotein 2 containing NeuAc. The results demonstrate that the hemagglutinins of human isolates of influenza viruses A and B differ in the recognition of microdomains (NeuAc, NeuGc) of the receptors for binding and fusion activities in viral penetration and the sequence to which sialic acid (SA) is attached (SA alpha 2-3Gal, SA alpha 2-6Gal). Inner I-active neolacto-series type II sugar chains may be important in revealing the receptor activity toward the hemagglutinin of both human influenza viruses A and B. 相似文献
17.
We synthesized the sialylphosphatidylethanolamine (sialyl PE) derivatives Neu5Ac-PE, (Neu5Ac)2-PE, Neu5Ac-PE (amide) and Neu5Ac-PE (methyl). We examined the anti-viral effects of the derivatives on human influenza A virus infection by ELISA/virus-binding, hemagglutination inhibition, hemolysis inhibition and neutralization assays. The sialyl PE derivatives that we examined bound to A/Aichi/2/68, A/Singapore/1/57 and A/Memphis/1/71 strains of H3N2 subtype, but not to A/PR/8/34 strain of H1N1 subtype. The derivatives inhibited viral hemagglutination and hemolysis of human erythrocytes with A/Aichi/2/68 and A/Singapore/1/57 (H3N2), but not with A/PR/8/34 (H1N1). The inhibitory activity of the (Neu5Ac)2-PE derivative was the strongest of all sialyl PE derivatives (IC50, 35 M to 40 M). Sialyl PE derivatives also inhibited the infection of A/Aichi/2/68 in MDCK cells. Complete inhibition was observed at a concentration between 0.3 to 1.3 mM. IC50 of (Neu5Ac)2-PE was 15 M in A/Aichi/2/68 strain. Taken together, the synthetic sialyl PE derivatives may be effective reagents against infection of some types of influenza A viruses. 相似文献
18.
The fluoro-hydrido-oxo complex [Re(F)(H)(O)Cyttp] + (3, Cyttp = PhP(CH 2CH 2CH 2PCy 2) 2) was prepared in high yield from [Re(H 2)H 4Cyttp]SbF 6 (1(SbF 6), NaSbF 6 and acetone in toluene at reflux. Reaction chemistry of 3 has been studied and, where appropriate, compared with that of the related dihydrido-oxo complex [ReH 2(O)Cyttp] + (2). Unlike 2, which readily reacts with both CO and SO 2, 3 was found to be inert to these reagents under comparable conditions. However, 3(SbF 6) reacts with NaSbF 6 at elevated temperature to afford the difluoro-oxo complex [ReF 2(O)Cyttp] + (4). 4 undergoes fluoride substitution by Cl − or Br − to yield [Re(X)(F)(O)Cyttp] + (X = Cl (5, Br (6)). 5 can also be obtained by treatment of 6(BPh 4) with LiCl. All of these complexes contain mer-Cyttp, and 3–6 contain trans fluoride and oxide ligands as inferred from spectroscopic data. 相似文献
19.
A method for the binding of virus to a silica gel thin-layer chromatogram is presented. After development the chromatogram is overlayed with the 125I-labelled virus and the bound virus is autoradiographed. Alternatively, the unlabelled virus may be detected after exposure to monoclonal antibody and labelled anti-antibody. The Sendai virus strain used did not bind to brain gangliosides earlier proposed to be receptors, but bound to human erythrocyte gangliosides. This finding may be explained by the existence of Sendai virus variants with different receptor specificities. 相似文献
20.
The potential in preparative chemistry of the precursors trans-[Ru(NH 3)(CC---R 1)(Ph 2PCH 2CH 2PPh 2) 2]PF 6 (3) has been studied. They offer a convenient access, by NH 3 displacement, to new functional alkynyl-ruthenium derivatives. Complexes 3 react with alkynes HCC---R 2 to give unsymmetrical trans-Ru(---CC---R 1)(---CC---R 2)(dppe) 2 compounds 4a-c, and with sodium methoxide in methanol they open the route to a variety of mixed hydride complexes 5a-c, trans-Ru(H)(---CC---R 1)(dppe) 2. In contrast, with carbon monoxide or isocyanides CN---R 3 (R 3:CH 2Ph, C 6H 11, Me 3C) they allow the preparation of cationic derivatives trans-(Ru(CO)(---CC---R 1)(dppe) 2]PF 6 (6a-c) or trans-[Ru(CNR 3)(---CC---R 1)(dppe) 2]PF 6 (7a-d). 相似文献
|