Several commercially available 2H-tetrazolium salts (TS) {2,3,5-triphenyl-2H-tetrazolium chloride (TTC), 3-(1-naphthyl)-2,5-diphenyl- 2H-tetrazolium chloride (Tetrazolium Violet, TV), ...3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT), 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl-2H-tetrazolium chloride (INT) and 3,3′-(3,3′-dimethoxy-4,4′-biphenylene)-bis(2,5-diphenyl- 2H-tetrazolium) chloride (Tetrazolium Blue Chloride, BTC)} and their ion-associated complexes (IAC) with the Mo(VI) — 4-nitrochatechol (4-NC) anionic chelate MoO
2
(4-NC)
2
2−
have been investigated by differential thermal analysis (DTA) and thermogravimetric analysis (TG). Some special features of the thermal behavior of the compounds have been discussed. The results show that the thermal stability of IAC depends on the factors determining the values of their association constants β: molecular mass and the presence of nitrophenyl substituent(s) in the tetrazolium ring.
Several commercially available 2H-tetrazolium salts (TS) {2,3,5-triphenyl-2H-tetrazolium chloride (TTC), 3-(1-naphthyl)-2,5-diphenyl- 2H-tetrazolium chloride (Tetrazolium Violet, TV), ...3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT), 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl-2H-tetrazolium chloride (INT) and 3,3'-(3,3'-dimethoxy-4,4'-biphenylene)-bis(2,5-diphenyl- 2H-tetrazolium) chloride (Tetrazolium Blue Chloride, BTC)} and their ion-associated complexes (IAC) with the Mo(VI) - 4-nitrochatechol (4-NC) anionic chelate MoO2(4-NC)2 have been investigated by differential thermal analysis (DTA) and thermogravimetric analysis (TG). Some special features of the thermal behavior of the compounds have been discussed. The results show that the thermal stability of IAC depends on the factors determining the values of their association constants beta: molecular mass and the presence of nitrophenyl substituent(s) in the tetrazolium ring.
HIV-1 envelope glycoprotein-mediated fusion is driven by the concerted coalescence of the HIV-1 gp41 N- and C-helical regions, which results in the formation of 6-helix bundles. These two regions are ...considered prime targets for peptides and antibodies that inhibit HIV-1 entry. However, the parameters that govern this inhibition have yet to be elucidated. We address this issue by monitoring the temporal sequence of conformational states of HIV-1 gp41 during the course of HIV-1-mediated cell−cell fusion by quantitative video microscopy using reagents that bind to N- and C-helical regions, respectively. Env-expressing cells were primed by incubation with target cells at different times at 37 °C followed by washing. The reactivity of triggered gp41 to the NC-1 monoclonal antibody, which we demonstrate here to bind to N-helical gp41 trimers, increased rapidly to a maximal level in the primed state but decreased once stable fusion junctions had formed. In contrast, reactivity with 5-helix, which binds to the C-helical region of gp41, increased continuously as a function of time following the priming. The peptide N36Mut(e,g) reduced NC-1 monoclonal antibody binding and enhanced 5-helix binding, consistent with the notion that this molecule promotes dissociation of gp41 trimers. This inactivation pathway may be important for the design of entry inhibitors and vaccine candidates.
We have previously identified neutralizing human monoclonal antibodies against Nipah virus (NiV) and Hendra virus (HeV) by panning a large nonimmune antibody library against a soluble form of the HeV ...attachment-envelope glycoprotein G (sGHeV). One of these antibodies, m102, which exhibited the highest level of cross-reactive neutralization of both NiV and HeV G, was affinity maturated by light-chain shuffling combined with random mutagenesis of its heavy-chain variable domain and panning against sGHeV. One of the selected antibody Fab clones, m102.4, had affinity of binding to sGHeV that was equal to or higher than that of the other Fabs; it was converted to IgG1 and tested against infectious NiV and HeV. It exhibited exceptionally potent and cross-reactive inhibitory activity with 50% inhibitory concentrations below 0.04 and 0.6 μg/mL, respectively. The virus-neutralizing activity correlated with the binding affinity of the antibody to sGHeV and sGNiV. m102.4 bound a soluble form of NiV G (sGNiV) better than it bound sGHeV, and it neutralized NiV better than HeV, despite being originally selected against sGHeV. These results suggest that m102.4 has potential as a therapeutic agent for the treatment of diseases caused by henipaviruses. It could be also used for prophylaxis and diagnosis, and as a research reagent
For closely related sequences there is a single optimal alignment which provides an accurate measure of similarity, structure, function and evolutionary history. However, with increasing evolutionary ...distances between nucleotide sequences the single optimal alignment method is replaced by an ensemble of alignments of almost equal quality and ensemble of different self-folded conformations.
Recurring difficulties associated with diverged sequence data include alternative alignment possibilities of insertions and deletions, region of length variations in which homology assessment is questionable or impossible, occurrence of localized excessive mutations to the point of saturation and lost of phylogenetic signals. Therefore, for diverged sequences optimizing similarity will not necessarily improve structure, function and evolutionary history assessments.
Here our aim is to present an overview of the methods involved in sequence analysis which are critical for current theoretical and application development. However, we do not follow historical events. For sequence comparison we focus on those methods that are based on exhaustive schemes, which are classically formulated as dynamic programming algorithms. They consist either of optimization schemes which find the best alignment for a given model, or of probabilistic schemes based on partition functions-in which all alignments, with their respective weights, are evaluated.
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