RESUMO
The selectins (lectin-EGF-complement binding-cell adhesion molecules [LEC-CAMs]) are a family of mammalian receptors implicated in the initial interactions between leukocytes and vascular endothelia, leading to lymphocyte homing, platelet binding, and neutrophil extravasation. The three known selectins, L-selectin (leukocyte adhesion molecule-1 [LECAM-1]), E-selectin (endothelial-leukocyte adhesion molecule-1 [ELAM-1]), and P-selectin (GMP-140) share structural features that include a calcium-dependent lectin domain. The sialyl Lewis(x) carbohydrate epitope has been reported as a ligand for both E- and P-selectins. Although L-selectin has been demonstrated to bind to carbohydrates, structural features of potential mammalian carbohydrate ligand(s) have not been well defined. Using an ELISA developed with a sialyl Lewis(x)-containing glycolipid and an E-selectin-IgG chimera, we have demonstrated the direct binding of the L-selectin-IgG chimera to sialyl Lewis(x). This recognition was calcium dependent, and could be blocked by Mel-14 antibody but not by other antibodies. Recognition was confirmed by the ability of cells expressing the native L-selectin to adhere to immobilized sialyl Lewis(x). These data suggest that the sialyl Lewis(x) oligosaccharide may form the basis of a recognition domain common to all three selectins.
Assuntos
Moléculas de Adesão Celular/metabolismo , Gangliosídeos/metabolismo , Antígenos CD15/metabolismo , Glicoproteínas da Membrana de Plaquetas/metabolismo , Animais , Sequência de Carboidratos , Adesão Celular , Células Cultivadas , Selectina E , Epitopos , Gangliosídeos/química , Técnicas In Vitro , Selectina L , Ligantes , Camundongos , Dados de Sequência Molecular , Selectina-P , Proteínas Recombinantes de Fusão/metabolismoRESUMO
The carbohydrate antigen, sialyl Lex, is known to be a ligand for the cell adhesion molecule called ELAM-1 (E-selectin, endothelial cell leukocyte adhesion molecule-1), which is present on cytokine-activated human endothelial cells. Recently, we reported that another carbohydrate antigen, sialyl Lea, can also serve as a ligand for ELAM-1 (A. Takada, K. Ohmori, N. Takahashi, K. Tsuyuoka, K. Yago, K. Zenita, A. Hasegawa, and R. Kannagi, Biochem. Biophys. Res. Commun., 179: 713-719, 1991). Both sialyl Lex and sialyl Lea are expressed in many human malignant cells. In order to assess the contribution of these carbohydrate antigens to the adhesion of human malignant cells to vascular endothelium, we selected a panel of 12 cultured human epithelial cancer cell lines and a panel of 12 human leukemia cell lines which express sialyl Lex and/or sialyl Lea antigens. All 12 epithelial cancer cell lines exhibited a clearly ELAM-1-dependent adhesion to cytokine-activated human umbilical vein endothelial cells, while only 3 of the 12 leukemia cell lines exhibited significant participation of ELAM-1 in the adhesion. With regard to epithelial cancer cells, the adhesion of 6 cancer cell lines, mostly of colon and pancreas origin, was dependent almost exclusively on sialyl Lea. A significant contribution of the sialyl Lex antigen was noted in the adhesion of the other 6 cell lines, including cancers of lung and liver origin. These results imply that the sialyl Lea/ELAM-1 adhesion system, as well as the sialyl Lex/ELAM-1 adhesion system, plays an important role in the adhesion of human cancer cells to human umbilical vein endothelial cells. With regard to leukemia cells, on the other hand, adhesion of the 3 leukemia cell lines that showed ELAM-1-dependent adhesion was mediated by the sialyl Lex antigen, and none of these leukemia cell lines expressed sialyl Lea or exhibited sialyl Lea-dependent adhesion.
Assuntos
Antígenos Glicosídicos Associados a Tumores/metabolismo , Adesão Celular , Endotélio Vascular/citologia , Antígenos do Grupo Sanguíneo de Lewis/fisiologia , Sequência de Carboidratos , Moléculas de Adesão Celular/metabolismo , Selectina E , Células Epiteliais , Humanos , Técnicas Imunológicas , Técnicas In Vitro , Molécula 1 de Adesão Intercelular , Interleucina-1/farmacologia , Dados de Sequência Molecular , Células Tumorais Cultivadas , Molécula 1 de Adesão de Célula VascularRESUMO
Highly pathogenic avian influenza (HPAI) viruses of the H5N1 subtype are enzootic in poultry populations in different parts of the world, and have caused numerous human infections in recent years, particularly in Egypt. However, no sustained human-to-human transmission of these viruses has yet been reported. We tested nine naturally occurring Egyptian H5N1 viruses (isolated in 2014-2015) in ferrets and found that three of them transmitted via respiratory droplets, causing a fatal infection in one of the exposed animals. All isolates were sensitive to neuraminidase inhibitors. However, these viruses were not transmitted via respiratory droplets in three additional transmission experiments in ferrets. Currently, we do not know if the efficiency of transmission is very low or if subtle differences in experimental parameters contributed to these inconsistent results. Nonetheless, our findings heighten concern regarding the pandemic potential of recent Egyptian H5N1 influenza viruses.
Assuntos
Virus da Influenza A Subtipo H5N1/genética , Infecções por Orthomyxoviridae/epidemiologia , Infecções por Orthomyxoviridae/veterinária , Animais , Antivirais/farmacologia , Bioensaio , Cães , Egito/epidemiologia , Inibidores Enzimáticos/farmacologia , Furões , Expressão Gênica , Células HeLa , Humanos , Virus da Influenza A Subtipo H5N1/classificação , Virus da Influenza A Subtipo H5N1/efeitos dos fármacos , Virus da Influenza A Subtipo H5N1/isolamento & purificação , Células Madin Darby de Rim Canino , Neuraminidase/antagonistas & inibidores , Neuraminidase/genética , Neuraminidase/metabolismo , Infecções por Orthomyxoviridae/tratamento farmacológico , Infecções por Orthomyxoviridae/transmissão , Filogenia , Medição de Risco , Carga Viral/efeitos dos fármacos , Proteínas Virais/antagonistas & inibidores , Proteínas Virais/genética , Proteínas Virais/metabolismoRESUMO
The effect of chemical modification at the C1 position of GLA-27, 4-O-phosphono-D-glucosamine carrying N-3-tetradecanoyloxytetradecanoyl [C14-O-(C14)] and 3-O-tetradecanoyl (C14) groups, was investigated. Replacement by SH or S-acetyl groups of the OH group resulted in the enhancement of mitogenicity but gave rise to a reduction, in macrophage-stimulating ability such as induction of tumor necrosis factor and enhancement of phagocytic and cellular acid phosphatase activities. Bisphosphorylation at C1 and C4 resulted in a slight decrease in mitogenicity or almost complete loss of the macrophage-stimulating ability.
Assuntos
Glucosamina , Lipídeo A/análogos & derivados , Lipídeo A/síntese química , Mitógenos/síntese química , Fator de Necrose Tumoral alfa/sangue , Animais , Divisão Celular/efeitos dos fármacos , Células Cultivadas , Replicação do DNA/efeitos dos fármacos , Lipídeo A/farmacologia , Camundongos , Camundongos Endogâmicos C3H , Relação Estrutura-Atividade , Timidina/metabolismoRESUMO
Biological activities of five synthetic lipid A analogues (D-glucosamine derivatives) were examined to elucidate the structure required for expression of the biological activities of endotoxin. Proclotting enzyme of horseshoe crab activation, interferon-inducing and tumor necrosis factor-inducing activities were significantly expressed by an analogue which possesses 4-O-phosphoryl, 3-O-tetradecanoyl and N-tetradecanoyloxytetradecanoyl groups. The results obtained with different analogues show that the 4-O-phosphoryl and N-tetradecanoyloxytetradecanoyl groups are important for expression of the above activities. The effect of 6-O-acylation in preventing the expression of these biological activities is also suggested. Pyrogenic activity was not detected in any of the compounds tested.
Assuntos
Lipídeo A , Animais , Feminino , Glucosamina/análogos & derivados , Glicoproteínas/biossíntese , Indutores de Interferon , Teste do Limulus , Camundongos , Pirogênios , Coelhos , Relação Estrutura-Atividade , Fator de Necrose Tumoral alfaRESUMO
Sialic acids are essential components of cell surface receptors used by influenza viruses. To determine the molecular mechanisms of viral recognition of two major species of sialic acids, N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc), we tested the binding reactivity of nine human H3 influenza A viruses to sialylglycolipids containing type II sugar chain and different molecular species of terminal sialic acids. All human H3 viruses tested except A/Memphis/1/71 bound both Neu5Ac and Neu5Gc. Nucleotide sequence analysis suggests that amino acids at 143, 155, and 158 are linked to the viral recognition of Neu5Gc.
Assuntos
Hemaglutininas/química , Vírus da Influenza A/química , Ácidos Neuramínicos/metabolismo , Sialoglicoproteínas/metabolismo , Sequência de Aminoácidos , Sequência de Carboidratos , Cromatografia em Camada Fina , Glicoconjugados/metabolismo , Humanos , Modelos Moleculares , Dados de Sequência Molecular , Homologia de Sequência de Aminoácidos , Proteínas Virais/metabolismoRESUMO
Originally discovered as a minor by-product of 6-sulfo-N-acetylsialyl Lewis(x) , the de-N-acetylated form 1 is a superior L-selectin ligand to the N-acetyl form. To substantiate the extraordinary reactivity of 1, it was synthesized for the first time and its binding to L-selectin investigated. Compound 1 and related structures may be high-affinity endogenous ligands for L-selectin that are involved in the interaction of leukocytes with the vascular endothelium.
RESUMO
Through a computer modeling and simulation technique, we investigated the binding mode of a complex of E-selectin-GSC-150, which is a novel selectin blocker. GSC-150 is the 3'-sulfated Lewis X derivative with a long, branched alkyl chain. Initial attempts to construct a model for E-selectin-GSC-150 complex were performed based on a previously reported model of E-selectin-sialyl Lewis X (sLex) complex [Kogan, T.P.; Revelle, B.M.; Tapp, S.; Scott, D.; Beck, P.J.J. Biol. Chem. 1995, 270, 14047-14055]. In our model, the carbohydrate portion of GSC-150 interacted with the protein in a similar manner as that of sLex reported previously. Interestingly, each of the branched alkyl chains extended on the surface of E-selectin and interacted with two different hydrophobic portions. One of these hydrophobic portions consists of Tyr44, Pro46, and Tyr48. Another portion forms a shallow cavity, and it consists of Ala9, Leu114, and the alkyl moieties of the side chains of Lys111, Lys112, and Lys113. A subsequent 200-ps molecular dynamics simulation in solution revealed that the interactions involved in the sugar portion of the ligand were relatively weak, whereas the hydrophobic interactions involved in the branched alkyl chains were fairly stable in solution. These results suggest that the branched alkyl chain serves as an "anchor" for the tight binding of GSC-150 on the surface of E-Selectin. This is the first attempt to evaluate the dynamics of E-Selectin-ligand interactions in solution, and it sheds light on the nature of ligand recognition by selectins.
Assuntos
Selectina E/metabolismo , Glicoesfingolipídeos/metabolismo , Oligossacarídeos/metabolismo , Sequência de Carboidratos , Simulação por Computador , Glicoesfingolipídeos/química , Lectinas/metabolismo , Ligantes , Modelos Moleculares , Conformação Molecular , Dados de Sequência Molecular , Estrutura Molecular , Antígeno Sialil Lewis X , Sulfatos/metabolismoRESUMO
As part of our studies of selectin blockers, we prepared 1-deoxy-3'-O-sulfo LeX analogs (1-3), 1-deoxy-3'-O-phosphono LeX analogs (4), and 1-deoxy sLeX analogs (5-7), and examined their inhibitory activities against natural ligand (sLeX) binding to E-selectin, P-selectin, and L-selectin. The 1-deoxy sLeX 5 was up to 20 times more potent an inhibitor than the sLeX tetrasaccharide toward P- and L-selectin binding. This indicates that the modification of the 1 or 2 position of sLeX is useful in the design of a more potent selectin blocker.
Assuntos
Selectina E/metabolismo , Selectina L/metabolismo , Antígenos CD15/farmacologia , Selectina-P/metabolismo , Conformação Molecular , Relação Estrutura-AtividadeRESUMO
As a part of our studies of selectin blockers, we prepared 1-(2-tetradecylhexadecyl)-3'-O-sulfo Le(X) 1 and 1-(2-tetradecylhexadecyl) sLe(X) 2 and examined their inhibitory activities against natural ligand (sLe(X)) binding to E-, P-, and L-selectins. Compounds 1 and 2 were 2 times more potent than the sLe(X) tetrasaccharide toward E-selectin binding and up to 4 times more potent than sLe(X) toward P- and L-selectin binding. Interestingly, compound 1 provided dose-dependent protective effects against an immunoglobulin E-mediated skin reaction in mouse ears. This protective effect was associated with diminished tissue accumulation of neutrophils in the ear (as assessed by myeloperoxidase). These findings indicate that the modification of sLe(X) or 3'-O-sulfo Le(X) with a "branched anchor", a 2-tetradecylhexadecyl group, is useful in the design of a more potent selectin blocker, which has broad inhibitory activities toward all selectins.
Assuntos
Anti-Inflamatórios não Esteroides/uso terapêutico , Inflamação/tratamento farmacológico , Oligossacarídeos/farmacologia , Selectinas/efeitos dos fármacos , Ésteres do Ácido Sulfúrico/farmacologia , Animais , Anti-Inflamatórios não Esteroides/química , Sequência de Carboidratos , Feminino , Espectroscopia de Ressonância Magnética , Camundongos , Camundongos Endogâmicos BALB C , Dados de Sequência Molecular , Oligossacarídeos/química , Ésteres do Ácido Sulfúrico/químicaRESUMO
Amyloid-beta protein (A beta) is known to induce microglial activation with concomitant release of cytokines. Gangliosides have documented neuritogenic and neurotrophic properties. We determined the effects of A beta on the release of interleukin-1beta (IL-1beta) from the human monocytic cell line, THP-1 cells. A beta 1-42 significantly induced the release of IL-1beta from the cells. A beta 1-40, A beta 40-1, A beta 1-38, and A beta precursor protein (beta-APP) analogs also released a small amount of IL-1beta. A beta 1-42-activated cells demonstrated approx an 18-fold higher IL-1beta release than that for control cells or A beta 1-40 (soluble; S) treated cells. The release of IL-1beta from A beta 1-42-activated cells was significantly inhibited (33-48% of activated cells; p < 0.05 for the control value) by addition of gangliosides, suggesting that gangliosides inhibit the continuous cycle of the IL-1beta production in THP-1 cells.
Assuntos
Peptídeos beta-Amiloides/metabolismo , Gangliosídeos/metabolismo , Interleucina-1/metabolismo , Monócitos/metabolismo , Peptídeos beta-Amiloides/farmacologia , Linhagem Celular , Relação Dose-Resposta a Droga , Gangliosídeos/farmacologia , Humanos , Monócitos/efeitos dos fármacos , Conformação Proteica , Fatores de TempoRESUMO
Protection against vaccinia virus infection and induction of interferon (IFN) were investigated in Propionibacterium acnes-primed mice following treatment with chemically synthesized lipid A-subunit derivatives. The antiviral activity was based on the reduction of numbers of tail lesions in mice injected intravenously with the test compounds 1 day before virus infection. GLA-27, a 4-O-phosphono-D-glucosamine carrying 3-O-tetradecanoyl (C14) and N-3-tetradecanoyloxytetradecanoyl [C14-O-(C14)] groups, offered significant antiviral activity. Chemical modifications at the C1 position of GLA-27, e.g. phosphorylation, replacement of OH by an SH, did not cause a significant change in antiviral activity. GLA-57 carrying an N-3-dodecanoyloxytetradecanoyl group showed stronger activity than GLA-27, but GLA-58 carrying an N-3-hexadecanoyloxytetradecanoyl group did not exhibit significant activity. GLA-59 carrying 3-O-3-hydroxytetradecanoyl and N-C14-O-(C14) groups was more active than GLA-27 and GLA-57. GLA-60 possessing the same fatty acid substituents as GLA-59 but in the reversed order was the most active of all compounds tested. This suggests that the nature and position of the acyl substituents are important for achieving the antiviral effects. The (R) isomers of GLA-59 and GLA-60 possessed stronger IFN-inducing activity than the (S) isomers, but no significant difference in antiviral activity was seen between the isomers.
Assuntos
Interferons/biossíntese , Lipídeo A/análogos & derivados , Vaccinia virus/imunologia , Vacínia/imunologia , Animais , Linhagem Celular , Feminino , Células HeLa , Humanos , Lipídeo A/imunologia , Camundongos , Camundongos Endogâmicos ICR , Estrutura Molecular , Vacínia/prevenção & controle , Vaccinia virus/crescimento & desenvolvimento , Ensaio de Placa ViralRESUMO
Biological and antiviral activities of chemically synthesized lipid A-subunit analogues, GLA-27 and GLA-60, were investigated with respect to defense mechanisms such as macrophage and natural killer (NK) cell activation and interferon (IFN)-inducing activity. GLA-27, a 4-O-phosphono-D-glucosamine derivative carrying 3-O-tetradecanoyl (C14) and 2-N-3-tetradecanoyloxytetradecanoyl (C14-O-(C14] group, and GLA-60, a similar analogue carrying 3-O-linked C14-O-(C14) and 2-N-linked 3-hydroxytetradecanoyl (C14-OH) groups, strongly inhibited the formation of pox tail lesions and the growth of vaccinia virus at the tail lesion sites in infected mice. The antiviral activity of GLA-60 was about 1000-fold higher than that of muramyldipeptide (MDP), a representative immunomodulator. GLA-27 and GLA-60 had stronger immunomodulating activity than MDP in macrophage activation, NK cell activation and IFN-inducing activity, although it was weaker than natural lipid A. Toxic manifestations such as pyrogenicity, local Schwartzman reaction and lethality were far less pronounced for GLA-27 and GLA-60 than for natural lipid A.
Assuntos
Adjuvantes Imunológicos , Antivirais , Lipídeo A/análogos & derivados , Acetilmuramil-Alanil-Isoglutamina/farmacologia , Animais , Feminino , Técnicas In Vitro , Indutores de Interferon , Células Matadoras Naturais/efeitos dos fármacos , Lipídeo A/farmacologia , Lipídeo A/toxicidade , Ativação de Macrófagos/efeitos dos fármacos , Masculino , Camundongos , Coelhos , Vaccinia virus/efeitos dos fármacosRESUMO
Intraperitoneal administration of 10 micrograms GLA-60, a chemically synthesized lipid A analogue, to mice one day after treatment with 200 mg/kg of cyclophosphamide (CY) significantly increased the number of macrophages, lymphocytes and polymorphonuclear leukocytes (PMNs) in the peritoneal cavity. The intrinsic antiviral activity of macrophages against herpes simplex virus type 1 (HSV-1) as well as natural killer (NK) activity against YAC-1 target cells was stimulated by administration of GLA-60 to CY-immunosuppressed mice. When the mice were administered GLA-60 prior to HSV-1 infection, virus growth was inhibited and the mortality rate of infected mice was reduced. Thus, GLA-60 is a potent immunomodulator achieving its antiviral action through enhancement of nonspecific host defense mechanisms. Combined treatment of GLA-60 with the antiviral agent acyclovir (ACV) resulted in greater protection against HSV-1 in the CY-immunosuppressed mice than did single treatment with either GLA-60 or ACV.
Assuntos
Antivirais/farmacologia , Células Matadoras Naturais/imunologia , Lipídeo A/análogos & derivados , Macrófagos/imunologia , Simplexvirus/crescimento & desenvolvimento , Animais , Ciclofosfamida/farmacologia , Feminino , Herpes Simples/tratamento farmacológico , Terapia de Imunossupressão , Células Matadoras Naturais/efeitos dos fármacos , Lipídeo A/farmacologia , Lipídeo A/uso terapêutico , Macrófagos/efeitos dos fármacos , Macrófagos/microbiologia , Camundongos , Camundongos Endogâmicos , Simplexvirus/efeitos dos fármacosRESUMO
A chemically synthesized lipid A-subunit analogue, GLA-60, 2-deoxy-4-O-phosphono-2-[(3R)-3-hydroxytetradecanamido]-3-O-[(3R)- 3- tetradecanoyloxytetradecanoyl]-D-glucose, has many of the activities of endotoxin but has little toxicity. Then, compounds with various lengths of acyl side chain of the acyloxyacyl group at the 3-O position of GLA-60 were synthesized and evaluated for interferon (IFN)-inducing activity, natural killer (NK) cell activation and antiviral activity. The compounds with acyl side chains between C8 and C15 exhibited significant antiviral activity (inhibition of pox tail lesion formation in vaccinia virus-infected mice), serum IFN-inducing activity and NK cell activation. However, the compound carrying a C2 or a C16 acyl side chain did not exhibit these activities. The compounds with a C13 or C14 acyl side chain showed strong protective against herpes simplex virus type 1 in cyclophosphamide-immunosuppressed mice.
Assuntos
Antivirais/farmacologia , Lipídeo A/análogos & derivados , Acilação , Animais , Feminino , Herpes Simples/tratamento farmacológico , Herpes Simples/mortalidade , Interferons/biossíntese , Células Matadoras Naturais/efeitos dos fármacos , Lipídeo A/metabolismo , Lipídeo A/farmacologia , Camundongos , Simplexvirus/efeitos dos fármacos , Vacínia/tratamento farmacológico , Vaccinia virus/efeitos dos fármacosRESUMO
The sensitivity and specificity of two influenza C virus assays, solid-phase and overlay assays, were investigated using naturally occurring 9-O-acetylated GD(3), rat serum glycoproteins containing 60% of N-acetyl-9-O-acetylneuraminic acid, and synthetically O-acetylated sialylated compounds. The sensitivity of the solid-phase assay was higher for glycoproteins containing N-acetyl-9-O-acetylneuraminic acid than for gangliosides, and also differed for various 9-O-acetylated gangliosides. The overlay assay was less sensitive for all glycoconjugates tested. For virus recognition the presentation of the sialic acid within the molecule and the structure of the sialic acid are essential. Investigation of gangliosides from human melanomas and normal skin with the influenza C virus assay showed an increase of O-acetylation of sialic acids in most tumour samples and the occurrence of several O-acetylated gangliosides.
Assuntos
Cromatografia em Camada Fina/métodos , Gammainfluenzavirus/química , Gangliosídeos/análise , Melanoma/química , Ácidos Siálicos/análise , Acetilação , Animais , Sequência de Carboidratos , Bovinos , Gangliosídeo G(M3)/análogos & derivados , Gangliosídeo G(M3)/análise , Gangliosídeos/síntese química , Gangliosídeos/isolamento & purificação , Glicoconjugados/análise , Glicoconjugados/síntese química , Glicoproteínas/análise , Glicoproteínas/sangue , Humanos , Dados de Sequência Molecular , Metástase Neoplásica , Ratos , Sensibilidade e Especificidade , Pele/químicaRESUMO
A membrane-associated ganglioside-hydrolyzing sialidase was purified to apparent homogeneity from bovine brain. The enzyme was solubilized with Triton X-100 plus sodium cholate from the particulate fraction and purified over 100,000-fold by sequential chromatography on DEAE-cellulose, octyl-Sepharose, heparin-Sepharose, Sephacryl S-200, MonoQ, RCA-agarose, thiol-activated Sepharose, and ganglioside-affinity Sepharose. The final enzyme preparation exhibited a specific activity of 4,851.3 micromol/h/mg protein and an apparent molecular mass of 52 kDa on SDS-polyacrylamide gel electrophoresis. The enzyme preferentially hydrolyzed gangliosides other than GM1 and GM2 but demonstrated hardly any activity against glycoproteins and oligosaccharides. Gangliosides GD3, GD1a, and GT1b were much better substrates than GM3 and GD1b in the presence of Triton X-100, but the latter became more sensitive to the sialidase with addition of sodium cholate. The enzyme was activated by dithiothreitol, strongly inhibited by 4-hydroxy-mercuribenzoate, and firmly adsorbed to thiol-activated Sepharose, indicating that free sulfhydryl groups are essential for its catalytic activity. Subcellular fractionation experiments revealed that the enzyme is mainly located in the synaptosomal fraction.
Assuntos
Encéfalo/enzimologia , Neuraminidase/química , Neuraminidase/metabolismo , Animais , Encéfalo/ultraestrutura , Bovinos , Ácido Cólico , Ácidos Cólicos , Cromatografia em Gel , Eletroforese em Gel de Poliacrilamida , Gangliosídeos/metabolismo , Glicoproteínas/metabolismo , Cinética , Membranas , Peso Molecular , Neuraminidase/isolamento & purificação , Octoxinol , Oligossacarídeos/metabolismo , Especificidade por Substrato , Sinaptossomos/enzimologiaRESUMO
Analogues of the nonreducing sugar part of lipid A were chemically synthesized and tested for biological activities such as Limulus amebocyte lysate gelation, interferon- and tumor necrosis factor-induction, lethal toxicity in galactosamine-sensitized mice, and pyrogenicity. A 4-O-monophosphorylglucosamine derivative possessing 2-N-3-tetradecanoyl-oxytetradecanoyl and 3-O-tetradecanoyl groups (GLA-27) exhibited all activities tested except for pyrogenicity. Alteration of the acyl substituents or dephosphorylation as well as acylation or phosphorylation of the 6-OH caused most activities of GLA-27 to diminish or disappear altogether. On the other hand, the biological activities expressed by GLA-27 were not significantly affected even when the glucosamine backbone was changed to 1-deoxy type, epimer type at C-3 (allose form), or 3-amino type. These results indicate that the acyl substituents and the phosphorylation positions rather than the backbone structures in these partial structure analogues of lipid A affect the expression of biological activities of endotoxin. The results also clearly indicate that some biological activities of endotoxin can be expressed separately from pyrogenicity.
Assuntos
Lipídeo A/síntese química , Animais , Feminino , Galactosamina/toxicidade , Glicoproteínas/biossíntese , Indutores de Interferon , Teste do Limulus , Lipídeo A/farmacologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos ICR , Propionibacterium acnes/metabolismo , Pirogênios , Estimulação Química , Relação Estrutura-Atividade , Fatores de Tempo , Fator de Necrose Tumoral alfaRESUMO
Sialyl-linkage specificity of the sialidase of influenza B viruses isolated in different years from 1940 through 1990 (B/Lee/40,B/Setagaya/3/56,B/Tokyo/7/66,B/Kagoshima/1/68, B/Gifu/2/73, B/Kanagawa/3/76, B/Ibaraki/2/85, B/Yamagata/16/88, and B/Bangkok/163/90) was studied with N-acetylneuraminyl (alpha 2-3)- and (alpha 2-6)-lactoses, GM3 gangliosides containing the same sialyl-oligosaccharide sequences as sialyllactose, and also with type I and type II lacto-series gangliosides carrying Neu5Ac alpha 2-3Gal and NeuAc alpha 2-6Gal linkages as substrates. From an examination of up to nine strains, the sialidases of all viruses preferentially hydrolyze substrates with Neu5Ac alpha 2-3Gal linkage rather than the Neu5Ac alpha 2-6Gal linkage. It was found that the sialidase activity toward Neu5Ac alpha 2-6Gal linkage relative to Neu5Ac alpha 2-3Gal linkage is increased in later strains, whether sialyllactose or ganglioside is used as the substrate. These results suggested that the sialidase of influenza B virus isolates has shown a drift in linkage specificity which correlates with the year of isolation.
Assuntos
Gangliosídeos/metabolismo , Vírus da Influenza B/enzimologia , Lactose/análogos & derivados , Neuraminidase/metabolismo , Ácidos Siálicos/metabolismo , Animais , Configuração de Carboidratos , Sequência de Carboidratos , Embrião de Galinha , Gangliosídeos/química , Lactose/química , Lactose/metabolismo , Dados de Sequência Molecular , Ácidos Siálicos/química , Especificidade por SubstratoRESUMO
Recognition specificity for sialylsugar chains by the hemagglutinin of influenza B viruses isolated in different years from 1940 through 1990 (B/Lee/40, B/Setagaya/3/56, B/Tokyo/7/66, B/Kagoshima/1/68, B/Gifu/2/73, B/Kanagawa/3/76, B/Ibaraki/2/85, B/Yamagata/16/88, and B/Bangkok/163/90) was studied using 13 gangliosides. Reactivity of the viruses' hemagglutinin binding to gangliosides was determined by using thin-layer chromatography/virus-binding assay, and also by measuring virus binding to erythrocytes modified by incubation with gangliosides in terms of the absorbance of hemoglobin released from the infected cells. Eight strains preferentially recognized a novel ganglioside, carrying lacto-series type I and II sugar chains with the Neu5Ac alpha 2-6Gal linkage. It was found that B/Gifu/2/73 strain binds to lacto-series gangliosides containing Neu5Ac alpha 2-6Gal and Neu5Ac alpha 2-3Gal linkages. Other gangliosides studied, including GM4, GM3(alpha 2-3), GM3(alpha 2-6), GM2, GM1a, GD3, GD1a, GD1b, and GT1b, were poor receptors.