Neutral Base Research Articles

Isolable Si=B Analogue of a Vinyl Halide: A Building Block for Facile Access toward Silicon‐Boron Multiple Bonded Species

AbstractCompared to the outstanding development in the synthesis of Si−B single bonded species, borylsilanes and their application to organic synthesis, the chemistry of Si=B double bonded species, borasilenes and boratasilenes have only made little progress, first of all, due to the difficulties in accessing such double bonds. Herein we report the synthesis of the first Si=B analogue of a vinyl halide, a bromoboratasilene, via formal borylene insertion to the coordination sphere of a monoatomic Si(0) complex, using a dihaloborane as the borylene source. The treatment of bromoboratasilene toward neutral or anionic Lewis bases gives access to new boratasilenes, all of which were proved to possess significant Si=B double bond character by XRD analysis and DFT calculations. These results demonstrate exciting strategies to synthesize new types of Si=B double bonded species which should further progress the chemistry of boron, silicon‐containing molecules.

Importance of the Cysteine-Rich Domain of Snake Venom Prothrombin Activators: Insights Gained from Synthetic Neutralizing Antibodies.

Snake venoms are cocktails of biologically active molecules that have evolved to immobilize prey, but can also induce a severe pathology in humans that are bitten. While animal-derived polyclonal antivenoms are the primary treatment for snakebites, they often have limitations in efficacy and can cause severe adverse side effects. Building on recent efforts to develop improved antivenoms, notably through monoclonal antibodies, requires a comprehensive understanding of venom toxins. Among these toxins, snake venom metalloproteinases (SVMPs) play a pivotal role, particularly in viper envenomation, causing tissue damage, hemorrhage and coagulation disruption. One of the current challenges in the development of neutralizing monoclonal antibodies against SVMPs is the large size of the protein and the lack of existing knowledge of neutralizing epitopes. Here, we screened a synthetic human antibody library to isolate monoclonal antibodies against an SVMP from saw-scaled viper (genus Echis) venom. Upon characterization, several antibodies were identified that effectively blocked SVMP-mediated prothrombin activation. Cryo-electron microscopy revealed the structural basis of antibody-mediated neutralization, pinpointing the non-catalytic cysteine-rich domain of SVMPs as a crucial target. These findings emphasize the importance of understanding the molecular mechanisms of SVMPs to counter their toxic effects, thus advancing the development of more effective antivenoms.

Isolable Si=B Analogue of a Vinyl Halide: A Building Block for Facile Access toward Silicon-Boron Multiple Bonded Species.

Compared to the outstanding development in the synthesis of Si-B single bonded species, borylsilanes and their application to organic synthesis, the chemistry of Si=B double bonded species, borasilenes and boratasilenes have only made little progress, first of all, due to the difficulties in accessing such double bonds. Herein we report the synthesis of the first Si=B analogue of a vinyl halide, a bromoboratasilene, via formal borylene insertion to the coordination sphere of a monoatomic Si(0) complex, using a dihaloborane as the borylene source.The treatment of bromoboratasilene toward neutral or anionic Lewis bases gives access to new boratasilenes, all of which were proved to possess significant Si=B double bond character by XRD analysis and DFT calculations. These results demonstrate exciting strategies to synthesize new types of Si=B double bonded species which should further progress the chemistry of boron, silicon-containing molecules.

Molecular insight into the neutralization mechanism of human-origin monoclonal antibody AH100 against Hantaan virus.

Both Old World and New World hantaviruses are transmitted through rodents and can lead to hemorrhagic fever with renal syndrome or hantavirus cardiopulmonary syndrome in humans without the availability of specific therapeutics. The square-shaped surface spikes of hantaviruses consist of four Gn-Gc heterodimers that are pivotal for viral entry into host cells and serve as targets for the immune system. Previously, a human-derived neutralizing monoclonal antibody, AH100, demonstrated specific neutralization against the Old World hantavirus, Hantaan virus. However, the precise mode binding of this neutralizing monoclonal antibody remains unclear. In the present study, we determined the structure of the Hantaan virus Gn-AH100 antigen-binding fragment complex and identified its epitope. Crystallography revealed that AH100 targeted the epitopes on domain A and b-ribbon and E3-like domain. Epitope mapping onto a model of the higher order (Gn-Gc)4 spike revealed its localization between neighboring Gn protomers, distinguishing this epitope as a unique site compared to the previously reported monoclonal antibodies. This study provides crucial insights into the structural basis of hantavirus neutralizing antibody epitopes, thereby facilitating the development of therapeutic antibodies.IMPORTANCEHantaan virus (HTNV) poses a significant threat to humans by causing hemorrhagic fever with renal syndrome with high mortality rates. In the absence of FDA-approved drugs or vaccines, it is urgent to develop specific therapeutics. Here, we elucidated the epitope of a human-derived neutralizing antibody, AH100, by determining the HTNV glycoprotein Gn-AH100 antigen-binding fragment (Fab) complex structure. Our findings revealed that the epitopes situated on the domain A and b-ribbon and E3-like domain of the HTNV Gn head. By modeling the complex structure in the viral lattice, we propose that AH100 neutralizes the virus by impeding conformational changes of Gn protomer, which is crucial for viral entry. Additionally, sequence analysis of all reported natural isolates indicated the absence of mutations in epitope residues, suggesting the potential neutralization ability of AH100 in diverse isolates. Therefore, our results provide novel insights into the epitope and the molecular basis of AH100 neutralization.

Structural basis for potent neutralization of human respirovirus type 3 by protective single-domain camelid antibodies

Respirovirus 3 is a leading cause of severe acute respiratory infections in vulnerable human populations. Entry into host cells is facilitated by the attachment glycoprotein and the fusion glycoprotein (F). Because of its crucial role, F represents an attractive therapeutic target. Here, we identify 13 F-directed heavy-chain-only antibody fragments that neutralize recombinant respirovirus 3. High-resolution cryo-EM structures of antibody fragments bound to the prefusion conformation of F reveal three distinct, previously uncharacterized epitopes. All three antibody fragments bind quaternary epitopes on F, suggesting mechanisms for neutralization that may include stabilization of the prefusion conformation. Studies in cotton rats demonstrate the prophylactic efficacy of these antibody fragments in reducing viral load in the lungs and nasal passages. These data highlight the potential of heavy-chain-only antibody fragments as effective interventions against respirovirus 3 infection and identify neutralizing epitopes that can be targeted for therapeutic development.

Functional and structural basis of human parainfluenza virus type 3 neutralization with human monoclonal antibodies.

Human parainfluenza virus type 3 (hPIV3) is a respiratory pathogen that can cause severe disease in older people and infants. Currently, vaccines against hPIV3 are in clinical trials but none have been approved yet. The haemagglutinin-neuraminidase (HN) and fusion (F) surface glycoproteins of hPIV3 are major antigenic determinants. Here we describe naturally occurring potently neutralizing human antibodies directed against both surface glycoproteins of hPIV3. We isolated seven neutralizing HN-reactive antibodies and a pre-fusion conformation F-reactive antibody from human memory B cells. One HN-binding monoclonal antibody (mAb), designated PIV3-23, exhibited functional attributes including haemagglutination and neuraminidase inhibition. We also delineated the structural basis of neutralization for two HN and one F mAbs. MAbs that neutralized hPIV3 in vitro protected against infection and disease in vivo in a cotton rat model of hPIV3 infection, suggesting correlates of protection for hPIV3 and the potential clinical utility of these mAbs.

Substitution reactions in the acenaphthene analog of quino[7,8-h]quinoline and an unusual synthesis of the corresponding acenaphthylenes by tele-elimination.

The possibility of functionalization of dipyrido[3,2-e:2',3'-h]acenaphthene containing a quino[7,8-h]quinoline fragment and being a highly basic diazine analog of 1,8-bis(dimethylamino)naphthalene ("proton sponge") has been studied for the first time. In addition to the pronounced tendency of the title compound to form associates with an intramolecular hydrogen bond of the NHN type (new examples with the participation of pyridine rings, including self-associates are shown) and its inertness to amination reactions of the pyridine rings, the naphthalene core at positions 5(8) and the CH2CH2 bridge (dehydrogenation) undergo chemical modifications under mild conditions, giving the corresponding acenaphthylenes. The latter can also be obtained in an unusual way by tele-elimination from 5,8-dibromodipyridoacenaphthene by reaction with neutral or anionic bases.

WORST CHOICE FOR SCHOOL CHOICE: TUITION TAX CREDITS ARE A BAD IDEA AND DIRECT FUNDING IS WISER

School choice is on the rise, and states use various mechanisms to implement it. One prevalent mechanism is also a uniquely problematic one: the tax credit. Tax credits are deficient at equitably distributing a benefit like school choice; they are costly, and they invite fraud. Instead of using tax credits, states opting for school choice programs should use direct funding. Direct funding will more efficiently achieve the goals of school choice because it can be regulated like any other government benefit, even if it ends up subsidizing religious private schools. Tax credits’ prevalence is not inexplicable, of course. It is based on a prior legal understanding that states were constitutionally restricted from directly funding religious schools. Historically, states that wanted to include religious private schools in their school choice programs therefore felt pushed to use tax credits as their only constitutionally viable option. However, the landscape has changed. The Supreme Court held in 2022 that direct funding of religious private schools is not only constitutionally permissible, but it is required if a state funds non-religious private schools and provides no neutral basis for excluding religious ones. The initial reason for tax credits’ popularity therefore no longer exists; both tax credits and direct funding alike are constitutionally acceptable. It is time, therefore, to revisit the merits of tax credits and ask whether, knowing what we know now, it is worth disposing of them in favor of direct funding. This Article answers that question with a resounding yes. Tax credits carry significant disadvantages—specifically, inequitable distribution and difficulties in regulation—that direct funding does not. Now that the law is clear, states choosing to sponsor school choice should discontinue their use of tax credits in favor of direct funding.

Host-guest chemistry of tridentate Lewis acids based on tribenzotriquinacene.

Flexible poly-Lewis acids (PLA) based on the tribenzotriquinacene (TBTQ) scaffold have been synthesised. Hydrosilylation of 4b,8b,12b-triallyltribenzotriquinacene and subsequent exchange of the chlorine substituents with weaker coordinating triflate groups afforded a novel triple silyl-functionalised PLA. By regioselective hydroboration of triallyl-TBTQ with various organoboranes, PLAs with different Lewis acidities were obtained. The synthesised PLAs were combined with neutral bases in host-guest experiments. DOSY NMR spectroscopy was performed to elucidate the complexation process in solution. These experiments revealed a highly dynamic interaction between the boron-functionalised PLA and triazine. However, the addition of one equivalent of tris(dimethylphosphino(methyl))phenylsilane led to the formation of a 1 : 1 adduct, which was confirmed by diffusion experiments.

1,3-Dipolar cyclisation reactions of nitriles with sterically encumbered cyclic triphosphanes: synthesis and electronic structure of phosphorus-rich heterocycles with tunable colour.

We describe the synthesis, solid state and electronic structures of a series of tunable five-membered cationic and charge-neutral inorganic heterocycles featuring a P3CN core. 1-Aza-2,3,4-triphospholenium cations [(PR)3N(H)CR']+, [1R]+ (R' = Me, Ph, 4-MeOC6H4, 4-CF3C6H4) were formed as triflate salts by the formal [3 + 2]-cyclisation reactions of strained cyclic triphosphanes (PR)3 (R = t Bu, 2,4,6-Me3C6H2 (Mes), 2,6- i Pr2C6H3 (Dipp), 2,4,6- i Pr3C6H2 (Tipp)) with nitriles R'CN in the presence of triflic acid. The corresponding neutral free bases (PR)3NCR' (2R) were readily obtained by subsequent deprotonation with NEt3. The P3CN cores in 2R show an envelope conformation typical for cyclopentenes and present as yellow to orange compounds in the solid state as well as in solution depending on both substituents R and R' in (PR)3NCR'. The P3CN cores in [1R]+ show a significant deviation from planarity with increasing steric bulk of the R groups at phosphorus, which results in a decrease in the HOMO-LUMO gap and distinct low-energy UV-Visible absorption bands. This allows access to colours spanning red, blue, indigo, and magenta. TD-DFT calculations provide valuable insight into this phenomenon and indicate an intramolecular charge-transfer from the HOMO located on the P3 framework to the N[double bond, length as m-dash]C-R'-based LUMO in the cationic species. The cations [1R]+ represent rare examples of phosphorus-rich heterocycles with tunable colour, which can be incorporated into polymers by post-polymerization modification to afford coloured polymers, which demonstrate utility as both proton and ammonia sensors.

High-pH mobile phase in reversed-phase liquid chromatography-tandem mass spectrometry to improve the separation efficiency of aminoglycoside isomers.

In chromatography, the use of extreme conditions can often lead to unique separation selectivity. In this study, a highly basic mobile phase (pH > 11), which is not typically employed for reversed-phase liquid chromatography (RPLC), was utilized in RPLC-tandem mass spectrometry (MS/MS) to achieve effective separation between electrically neutral bases of aminoglycosides (AGs). A mixture of AGs was simultaneously analyzed using 500mmol L-1 ammonia aqueous solution (pH 11.8) as the mobile phase. A total of 11 AGs, including 2 stereoisomers of neomycin (B and C) and 5 structurally similar components of gentamicin (C1, C1a, C2, C2a, and C2b), were completely separated for the first time. The high separation performance for AGs was mainly due to two factors: First, slight differences in hydrophobicity among the AGs were significantly enhanced at a high pH by the complete acid dissociation of amines. Second, the high pH of the mobile phase minimized any electrostatic interactions between the AGs and residual silanol groups in the stationary phase, resulting in extremely sharp peaks for the AGs. The sensitivity of spectinomycin decreased by more than 20% when using the highly basic mobile phase (pH 11.8) due to its degradation, therefore, a mixture of 10 AGs was analyzed with 250mmol L-1 ammonia aqueous solution (pH 11.5) with less degradation as the optimum condition. The developed analytical method could be used to determine the concentrations of trace AGs in milk with high accuracy and precision. Thus, RPLC-MS/MS using a high-pH mobile phase has great potential for the efficient separation of basic compounds containing amino sugars such as AGs.

Boosting Phosphoric Acid Retention in Polymer Electrolyte Membranes by Zwitterions: Insights from DFT Calculations and MD Simulations.

Effective retention of phosphoric acid (PA) is crucial for the efficient operation of fuel cells based on PA-doped polymeric membranes, which is highly challenging due to the moisture-induced loss of PA. Therefore, a comprehensive understanding of the interplay among PA, functional groups, and water is essential for designing membrane materials. Using density functional theory (DFT) calculations and molecular dynamics (MD) simulations, we unveil the remarkable capability of zwitterions to effectively sequester PA, thereby unlocking the potential for fuel cell optimization. Our DFT calculations show that zwitterions, termed "charged proton-accepting bases", exhibit stronger interactions with PA compared to the traditional neutral proton-accepting bases. Furthermore, the presence of water amplifies such a discrepancy, with the zwitterion-PA interactions playing a dominant role in the zwitterion-PA-water cluster due to the strongest affinity of zwitterions to PA. Conversely, the ability of neutral bases to retain PA is significantly attenuated by moisture as the interactions between water and PA surpass those between neutral bases and PA. The strong zwitterion-PA associations arise primarily from the formation of multiple hydrogen bonds. Furthermore, MD simulations reveal the uniform distribution of zwitterions in aqueous environments and their pronounced affinities for both PA and water. In contrast, neutral bases tend to aggregate, interacting limitedly with PA. These findings underscore the effectiveness of zwitterions in boosting PA retention in fuel cells.

G-C3N4/Bromocobaloxime nanocomposites as multi-functional electrocatalysts for water splitting and energy storage

The depletion of fossil fuels necessitates the search for alternative sources of energy and energy storage for long-term usage. Recently graphitic carbon nitride (g-C3N4) based materials have gained attention due to their enhanced activity compared to previously tested materials. But the poor electron mobility of g-C3N4 continues to cause a significant energy loss in the electrocatalytic processes. Herein we report the synthesis and characterization of g-C3N4/Bromocobaloxime composites and their electrocatalytic applications towards hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and energy storage. Bromocobaloximes [BrCo(dpgH)2B] (B1-B4) containing diphenylglyoxime [dpgH] as the equatorial ligand and functionalized neutral bases such as Isonicotinic acid (1), Pyridine-3,5-dicarboxylic acid (2), Indole-2-carboxylic acid (3) and p-Aminobenzoic acid (4) were synthesized using the standard procedure. The g-C3N4/Cobaloxime nanocomposites (g-C3N4/B1, g-C3N4/B2, g-C3N4/B3 and g-C3N4/B4) were prepared using g-C3N4 nanosheets by solvothermal method. The prepared nanocomposites were characterized by FT-IR, UV-DRS, XRD, SEM, EDAX, TEM and XPS analysis. The electrochemical HER studies of the synthesized nanocomposites showed low overpotentials in the range of 51 to 228 mV at −10 mAcm−2 and the OER studies exhibited overpotentials in the range of 310 to 460 mV at 10 mAcm−2. Among them nanocomposite g-C3N4/B2 showed a lower Tafel slope of 45 mV/dec for HER and 112 mV/dec for OER. The supercapacitance studies indicated that among the nanocomposites, g-C3N4/B1 showed a good specific capacitance of 302 F/g at 0.5 A/g. The increased electrochemical performance of the synthesized nanocomposites is due to the incorporation of cobaloximes containing carboxylic acid functionalized neutral bases into the g-C3N4 nanosheets, which increases the electron mobility. This will lead to explore the applications of g-C3N4/metal complexes towards energy conversion by tuning the ligands in the metal complexes.

On Prototropy and Bond Length Alternation in Neutral and Ionized Pyrimidine Bases and Their Model Azines in Vacuo

In this review, the complete tautomeric equilibria are derived for disubstituted pyrimidine nucleic acid bases starting from phenol, aniline, and their model compounds—monosubstituted aromatic azines. The differences in tautomeric preferences for isolated (gaseous) neutral pyrimidine bases and their model compounds are discussed in light of different functional groups, their positions within the six-membered ring, electronic effects, and intramolecular interactions. For the discussion of tautomeric preferences and for the analysis of internal effects, recent quantum-chemical results are taken into account and compared to some experimental ones. For each possible tautomer-rotamer of the title compounds, the bond length alternation, measured by means of the harmonic oscillator model of electron delocalization (HOMED) index, is examined. Significant HOMED similarities exist for mono- and disubstituted derivatives. The lack of parallelism between the geometric (HOMED) and energetic (ΔG) parameters for all possible isomers clearly shows that aromaticity is not the main factor that dictates tautomeric preferences for pyrimidine bases, particularly for uracil and thymine. The effects of one-electron loss (positive ionization) and one-electron gain (negative ionization) on prototropy and bond length alternation are also reviewed for pyrimidine bases and their models.

Structural basis for broad neutralization of human antibody against Omicron sublineages and evasion by XBB variant.

The ongoing COVID-19 pandemic has been characterized by the emergence of new SARS-CoV-2 variants including the highly transmissible Omicron XBB sublineages, which have shown significant resistance to neutralizing antibodies (nAbs). This resistance has led to decreased vaccine effectiveness and therefore result in breakthrough infections and reinfections, which continuously threaten public health. To date, almost all available therapeutic nAbs, including those authorized under Emergency Use Authorization nAbs that were previously clinically useful against early strains, have recently been found to be ineffective against newly emerging variants. In this study, we provide a comprehensive structural basis about how the Class 3 nAbs, including 1G11 in this study and noted LY-CoV1404, are evaded by the newly emerged SARS-CoV-2 variants.

Yttrium Complexes with Group 13 Heterobenzene-Type Ligands.

The yttrium gallabenzene complex [(1-Me-3,5-tBu2 -C5 H3 Ga)(μ-Me)Y(2,4-dtbp)] is accessible from Y(GaMe4 )3 and K(2,4-dtbp) via a tandem salt metathesis/methane elimination (2,4-dtbp=2,4-di-tert-butyl-pentadienyl). The pentadienyl ligand in [(1-Me-3,5-tBu2 -C5 H3 E)(μ-Me)Y(2,4-dtbp)] (E=Al, Ga) is easily displaced by salt metathesis with KC5 Me5 and KTpMe,Me (TpMe,Me =tris(pyrazolyl-Me2 -3,5)borato) affording [(1-Me-3,5-tBu2 -C5 H3 E)(μ-Me)Y(TpMe,Me )] and [(1-Me-3,5-tBu2 -C5 H3 E)(μ-Me)Y(C5 Me5 )]. The yttrium center in [(1-Me-3,5-tBu2 -C5 H3 E)(μ-Me)Y(2,4-dtbp)] readily forms adducts with neutral Lewis bases like 4-DMAP (4-dimethylaminopyridine), PMe3 , DMPE (1,2-bis(dimethylphosphino)ethane), and DME (1,2-dimethoxyethane). In stark contrast, addition of TMEDA (N,N,N',N'-tetramethylethylenediamine) results in methyl/pentadienyl exchange between aluminum and yttrium resulting in [(1-(2,4-dtbp)-1-Me-3,5-tBu2 -C5 H3 Al)Y(Me)(tmeda)]. The bonding features of the newly synthesized complexes are analyzed by single-crystal X-ray diffraction (SCXRD) and heteronuclear (89 Y, 31 P) NMR spectroscopy.

G-C3N4/Chlorocobaloxime Nanocomposites as Multifunctional Electrocatalysts for Water Splitting and Energy Storage.

Due to environmental contamination and the depletion of energy supplies, it is very important to develop low-cost, high-performance, multifunctional electrocatalysts for energy conversion and storage systems. Herein, we report the development of cost-effective modified electrodes containing g-C3N4/chlorocobaloxime composites (C1-C4) and their electrocatalytic behavior toward the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), followed by their energy-storage applications. A series of chlorocobaloximes {ClCo(dpgH)2B} with diphenylglyoxime (dpgH) and neutral bases (B) containing a carboxylic acid moiety (isonicotinic acid, pyridine-3,5-dicarboxylic acid, indole-2-carboxylic acid, and p-aminobenzoic acid) have been synthesized and characterized by spectroscopic techniques. The nanocomposites of g-C3N4/chlorocobaloximes are prepared and characterized by Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (UV-DRS), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS), particle size distribution analysis (PSA), Brunauer-Emmett-Teller (BET), and energy dispersive X-ray analysis (EDAX) techniques. The composite coatings exhibit enhanced HER performance at lower overpotential and with a lower Tafel slope. When the water-splitting reactions are studied using 0.5 M H2SO4 and 0.5 M KOH as electrolytic solutions, the composite g-C3N4/C2 containing pyridine-3,5-dicarboxylic acid as a neutral base shows excellent HER activity with a lower overpotential of 173 mV at -10 mA cm-2 and OER activity with a lower overpotential of 303 mV. The HER reaction takes place through the Volmer-Heyrovský mechanism, where the desorption step is the rate-determining step. Among the synthesized nanocomposites, the nanocomposite g-C3N4/C2 shows higher efficiency toward both HER and OER reactions, with a lower Tafel slope of 55 mV dec-1 for HER and 114 mV dec-1 for OER than the other nanocomposites. The overall water-splitting studies of the composite g-C3N4/C2 in 0.5 M KOH indicate that the evolution of hydrogen and oxygen occurs constantly up to 120 h. The supercapacitance applications studied using cyclic voltammetry and charge-discharge studies indicate that the nanocomposite g-C3N4/C1 shows a good specific capacitance of 236 F g-1 at 0.5 A g-1 compared to others. The increased electrochemical performance of the synthesized nanocomposites is due to the incorporation of electron-withdrawing carboxylic-acid-functionalized neutral bases present in cobaloximes, which increases electron mobility. The incorporation of a cobaloxime complex into a g-C3N4 nanosheet enhances the electrocatalytic behavior of the nanosheet, and its performance can further be fine-tuned by systematic variation in the structure of cobaloxime by changing the halide ion, dioxime, the neutral base ligand, or the substituent.

The significance of a forum selection agreement as an indicator of the implied choice of law in international contracts: a global comparative perspective

Abstract Where the parties to an international contract fail to specify the choice of law, a forum selection agreement is one of the most, if not the most, significant factors to consider in implying the choice of law in many international, supranational, regional instruments, and national jurisdictions. However, it is an ill-defined, notoriously complex, and hotly debated issue as to the weight that should be attached to a forum selection agreement in implying the choice of law. Hence, this article is devoted to discussing this topic from a comparative perspective, in order to propose a guide to global uniform criteria. To achieve this, the article covers all relevant international, regional, and supranational instruments, and selected legal systems in Africa, Asia, Australasia, Europe, the Middle East, and North and South America. The legal systems compared include those from the global North and global South, including common law, civil law, and mixed legal systems. The article’s core proposal is that an exclusive forum selection agreement should be a key factor in implying the choice of law. However, except in such cases as where a forum is chosen on a neutral basis, there should be a general requirement of corroboration with at least one other factor of significance. The aim of the proposal is to contribute to greater uniformity, predictability, and certainty in the global community in this field of law.

Recognition determinants of improved HIV-1 neutralization by a heavy chain matured pediatric antibody

The structural and characteristic features of HIV-1 broadly neutralizing antibodies (bnAbs) from chronically infected pediatric donors are currently unknown. Herein, we characterized a heavy chain matured HIV-1 bnAb 44m, identified from a pediatric elite-neutralizer. Interestingly, in comparison to its wild-type AIIMS-P01 bnAb, 44m exhibited moderately higher level of somatic hypermutations of 15.2%. The 44m neutralized 79% of HIV-1 heterologous viruses (n= 58) tested, with a geometric mean IC50 titer of 0.36μg/mL. The cryo-EM structure of 44m Fab in complex with fully cleaved glycosylated native-like BG505.SOSIP.664.T332N gp140 envelope trimer at 4.4Å resolution revealed that 44m targets the V3-glycan N332-supersite and GDIR motif to neutralize HIV-1 with improved potency and breadth, plausibly attributed by a matured heavy chain as compared to that of wild-type AIIMS-P01. This study further improves our understanding on pediatric HIV-1 bnAbs and structural basis of broad HIV-1 neutralization by 44m may be useful blueprint for vaccine design in future.

The structural basis of hyperpromiscuity in a core combinatorial network of type II toxin–antitoxin and related phage defense systems

Toxin-antitoxin (TA) systems are a large group of small genetic modules found in prokaryotes and their mobile genetic elements. Type II TAs are encoded as bicistronic (two-gene) operons that encode two proteins: a toxin and a neutralizing antitoxin. Using our tool NetFlax (standing for Network-FlaGs for toxins and antitoxins), we have performed a large-scale bioinformatic analysis of proteinaceous TAs, revealing interconnected clusters constituting a core network of TA-like gene pairs. To understand the structural basis of toxin neutralization by antitoxins, we have predicted the structures of 3,419 complexes with AlphaFold2. Together with mutagenesis and functional assays, our structural predictions provide insights into the neutralizing mechanism of the hyperpromiscuous Panacea antitoxin domain. In antitoxins composed of standalone Panacea, the domain mediates direct toxin neutralization, while in multidomain antitoxins the neutralization is mediated by other domains, such as PAD1, Phd-C, and ZFD. We hypothesize that Panacea acts as a sensor that regulates TA activation. We have experimentally validated 16 NetFlax TA systems and used domain annotations and metabolic labeling assays to predict their potential mechanisms of toxicity (such as membrane disruption, and inhibition of cell division or protein synthesis) as well as biological functions (such as antiphage defense). We have validated the antiphage activity of a RosmerTA system encoded by Gordonia phage Kita, and used fluorescence microscopy to confirm its predicted membrane-depolarizing activity. The interactive version of the NetFlax TA network that includes structural predictions can be accessed at http://netflax.webflags.se/.