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891.
Gianfranco De Pieri Angelo Signor Gian Maria Bonora Claudio Toniolo 《International journal of biological macromolecules》1984,6(1):35-40
A circular dichroism investigation of two β-bend forming, Aib-containing tetrapeptides, with the -Aib-l-Ala- and -l-Ala-Aib- central sequences, occurring in peptaibol antibiotics, blocked at the N-terminal end with the 2,4-dinitrophenyl group and at the C-terminal end with the p-nitroanilino group, is described. A comparison is made with a tetrapeptide containing the -l-Ala-l-Ala- central sequence, also observed in peptaibol antibiotics. The amount of β-bend conformers, determined from the intensities of the exciton couplets arising from the intramolecular interaction of the p-nitroanilino chromophores, has been assessed as a function of the hydrogen-bonding properties of the solvent. The conformational analysis in dimethylsulphoxide has been extended to 1H nuclear magnetic resonance. Some information on the type of β-bend formed has additionally been obtained. The preparation and characterization of the three chromophoric tetrapeptides, along with some analogues and synthetic precursors, are also reported. 相似文献
892.
Olivier Missa Yves Basset Alfonso Alonso Scott E. Miller Gianfranco Curletti Marc De Meyer Connal Eardley Mervyn W. Mansell Thomas Wagner 《Journal of Insect Conservation》2009,13(1):103-118
To discuss the challenge of monitoring multi-species responses of tropical arthropods to disturbance, we considered a large
dataset (4 × 105 individuals; 1,682 morphospecies representing 22 focal taxa) based on the work of parataxonomists to examine the effects
of anthropogenic disturbance on arthropods at Gamba, Gabon. Replication included three sites in each of four different stages
of forest succession and land use after logging, surveyed during a whole year with four sampling methods: pitfall, Malaise,
flight-interception and yellow pan traps. We compared the suitability of each sampling method for biological monitoring and
evaluated statistically their reliability for 118 arthropod families. Our results suggest that a range of sampling methods
yields more diverse material than any single method operated with high replication. Multivariate analyses indicated that morphospecies
composition in trap catches was more strongly influenced by habitat type than by sampling methods. This implies that for multi-species
monitoring, differences in trap efficiency between habitats may be neglected, as far as habitat types remain well contrasted.
We conclude that for the purpose of monitoring large arthropod assemblages in the long-term, a protocol based on operating
a set of different and non-disruptive traps appears superior in design than summing a series of taxa-specific protocols. 相似文献
893.
Sabina Cauci Rossella Monte Monica Ropele Caterina Missero Tarcisio Not Franco Quadrifoglio Gianfranco Menestrina 《Molecular microbiology》1993,9(6):1143-1155
The pleomorphic bacterium Gardnerella vaginalis releases in the culture broth a haemolytic exotoxin (Gvh) which is probably a virulence determinant of this unique bacterium, implicated in gynaecological and urological disorders. This 59kDa cytolysin was purified to homogeneity in just one chromatographic step directly from the culture supernatant, a final specific activity up to 1.9 × 106 HU mg?1 being obtained. The toxin-induced lesion on human erythrocytes results from the formation of a pore whose radius is approximately 2.4 nm. The damage is inhibited by osmotic protectants and shows a sigmoidal dose-response profile suggesting an aggregation process of haemolysin molecules on the target membrane to create the functional lesion. The extent and the kinetics of haemolysis are strongly dependent on temperature and an activation energy of 64.0 kJ mol?1 has been derived. Lipid membranes can be very efficient inhibitors of Gvh-haemolysis, being able to bind the toxin quite avidly. The inhibitory effect requires the presence of cholesterol and it is stronger when cholesterol is mixed with negatively charged phospholipids rather than with zwitterionic phospholipids, suggesting that a negative surface potential increases the affinity of the toxin for the lipid bilayer. The functional properties of Gvh have been compared with those of Clostridium perfringens theta-toxin (PFO) and Escherichia coli haemolysin (HlyA), which are representative of widespread haemolysins produced by Gram-positive and Gram-negative bacteria, respectively. The toxin shares several features with the family of the so-called ‘sulphydryl-activated’ cytolysins produced by Gram-positive bacteria, although Gvh does not truly belong to this family, being deactivated by β-mercaptoethanol and being antigenically distinct from them. We report here for the first time the detection in the vaginal fluid of infected women of a specific IgA response against the toxin. 相似文献
894.
Albino Defilippi Gianfranco Piancone Riccardo Costa Laia Silvia Balla Gian Paolo Tibaldi 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1994,656(2)
A method for the determination of isonicotinic acid hydrazide (isoniazid) in milk was developed. Milk was deproteinized with trichloroacetic acid. Isoniazid was condensed with cinnamaldehyde and assayed on a reversed-phase HPLC system, with good sensitivity and accuracy (10 μg/l) with UV detection at 330 nm. Use of solid-phase extraction with a C18 cartridge allows the detection limit to be lowered to 0.1 μg/l with UV detection and confirmation of isoniazid hydrazone from the diode-array UV spectrum. 相似文献
895.
Syntheses are described for two N-benzyloxycarbonylpeptide tert-butoxycarbonylhydrazides which correspond to positions 24–34 and 35–44, respectively, of the primary structure of baker's yeast iso-1-cytochrome c. The two peptide derivatives were coupled via the azide procedure to form the N-benzyloxycarbonylheneicosapeptide tert-butoxycarbonylhydrazide (sequence 24–44). 相似文献
896.
Giampaolo Manao Luigia Pazzagli Paolo Cirri Anna Caselli Guido Camici Gianni Cappugi Ahmad Saeed Giampietro Ramponi 《The protein journal》1992,11(3):333-345
Two lowM r phosphotyrosine protein phosphatases have been isolated from rat liver. The enzymes were previously known as lowM r acid phosphatases, but several recent studies have demonstrated that this family of enzymes possesses specific phosphotyrosine protein phosphatase activity. We determined the complete amino acid sequences of the two isoenzymes and named them AcP1 and AcP2. Both consist of 157 amino acid residues, are acetylated at the NH2-terminus, and have His as the COOH-terminus. The molecular weights calculated from the sequences are 18,062 for AcP1 and 17,848 for AcP2. They are homologous except in the 40–73 zone, where about 50% of residues are different. This fact suggests that the two isoenzymes are produced by an alternative splicing mechanism. There is no homology between these two isoenzymes and the receptor-like phosphotyrosine protein phosphatases LAR, CD45, human placenta PTPase 1B, and rat brain PTPase-1. AcP1 and AcP2 are also distinct from rat liver PTPase-1 and PTPase-2, since these last enzymes have higher molecular weights. AcP1 differs from AcP2 with respect to (1) substrate affinity and (2) its sensitivity to activators and inhibitors, thus suggesting a their different physiological function. 相似文献
897.
898.
Awatef Allouch Cristina Di Primio Audrey Paoletti Gabrielle Lê-Bury Frdric Subra Valentina Quercioli Roberta Nardacci Annie David Hla Saïdi Anna Cereseto David M. Ojcius Guillaume Montagnac Florence Niedergang Gianfranco Pancino Asier Saez-Cirion Mauro Piacentini Marie-Lise Gougeon Guido Kroemer Jean-Luc Perfettini 《Cell death and differentiation》2020,27(12):3243
Understanding the viral–host cell interface during HIV-1 infection is a prerequisite for the development of innovative antiviral therapies. Here we show that the suppressor of G2 allele of skp1 (SUGT1) is a permissive factor for human immunodeficiency virus (HIV)-1 infection. Expression of SUGT1 increases in infected cells on human brain sections and in permissive host cells. We found that SUGT1 determines the permissiveness to infection of lymphocytes and macrophages by modulating the nuclear import of the viral genome. More importantly, SUGT1 stabilizes the microtubule plus-ends (+MTs) of host cells (through the modulation of microtubule acetylation and the formation of end-binding protein 1 (EB1) comets). This effect on microtubules favors HIV-1 retrograde trafficking and replication. SUGT1 depletion impairs the replication of HIV-1 patient primary isolates and mutant virus that is resistant to raltegravir antiretroviral agent. Altogether our results identify SUGT1 as a cellular factor involved in the post-entry steps of HIV-1 infection that may be targeted for new therapeutic approaches.Subject terms: Infectious diseases, Immunopathogenesis 相似文献
899.