ACS Publications最新文献

In situ precise matching of chiral structures (e.g., stereocomplementary pairs between secondary structures of proteins) is essential for directing the evolution of biostructures. To date, static construction of diverse stereoselective pairs (parallel homochiral or heterochiral helical array, homochiral double/triple helices, etc.) is realized by self-assembly. However, dynamically mastering helix coupling to direct structure evolution remains highly challenging due to the increased complexity of intricate chirality transfer and matching. Herein, we introduce stereochemical strategies (homochirality to racemization or mesomerization) to control heterochiral helix (P and M) coupling for evolving primary nanofibers into superstructures. A homochiral system is confined to initial nanofibers without evolution for over one year. In contrast, the racemization and mesomerization strategies can trigger evolution from nanofibers to superstructures after 7 h or 12 months, respectively, which are both driven by in situ generating heterochiral P-M helix coupling through the spatially matched hydrogen bonds. In a meso-system, the chiral transfer follows a strict unidirectional pathway: l-chiral terminals exclusively lead to M-helicity and D-terminals form P-helicity. However, L-fragments in a racemic system can assemble into both M and P helices through an additional conformational transformation facilitated by CH···π interactions between heterochiral fragments, revealing a rare bifurcated chirality transfer mechanism. Obviously, homochiral systems cannot achieve such helix coupling due to a lack of heterochiral interaction. This strategy thus opens a stereochemistry-controlled avenue to the in situ control of helical pairs for structural evolution.

We illustrate the potential of a pair of steady-state ion mobility filters run in series, similar to a triple quadrupole mass spectrometer, not only to operate under atmospheric pressure but also to determine reaction kinetics at controlled pressure and temperature. Singly charged cluster cations of the ionic liquid 1-ethyl-3-methyl-imidazolium tris(pentafluoroethyl)trifluorophosphate (EMI-FAP) produced by a bipolar electrospray source are isolated steadily at atmospheric pressure by a first ion mobility spectrometer (IMS). A second IMS then determines the composition of evaporative decay products: (EMI-FAP)_n-1EMI⁺→(EMI-FAP)_n-2EMI⁺+EMI-FAP (2 ≤ n ≤ 30) after passing through a heated parabolic flow reactor tube at controlled temperatures T (23-40 °C). Measured product/parent abundance ratios are converted into reaction constants k_n via a previously described theory. At n < 11, evaporation rates k_n exhibit idiosyncrasies characteristic of various magic numbers, some of which are also reflected in a cluster compactness parameter inferred from the measured mobility cross section and mass. An approximately continuous variation of volatility with n is found for 11 ≤ n ≤ 14, and for n ≥ 19, with a region of low volatility in between. This especially stable domain of four clusters (15 ≤ n ≤ 18) is reached on the right (n = 18) with a discontinuous (4-fold) volatility decrease, suggesting a transition to a liquid-like structure. On the left it merges continuously (though with a steep slope) with the trend at smaller sizes (11 ≤ n ≤ 14).

A challenge exists in the solution-phase construction of chiral functional materials via halogen bonding, largely due to the pronounced disruptive influence of solvation on conventional halogen bonding interactions. In this work, we describe halogen bond-mediated chirality induction in solution, enabling the construction of discrete-state chiroptical materials with tunable properties and broad substrate versatility. A central chiral site was introduced into a cyclic hypervalent iodine(III) scaffold (denoted as I(III)), which individually assembles into cationic antielectrostatic halogen-bonded dimers in the solid state and low-polarity solvents, stabilized by a quadrupled halogen and hydrogen bonding network. I(III) exhibits strong binding affinity toward both neutral and anionic halogen bond acceptors, with association constants on the order of ∼10⁴ M^-1. This robust interaction enables efficient chirality induction in both the ground and excited states. The resulting halogen-bonded complexes display solvent-responsive behavior, exhibiting mirror-image chiroptical properties in dichloromethane and tetrahydrofuran. It demonstrates excellent adaptability toward diverse halogen bond acceptors, enabling effective chirality induction across a range of systems. This versatility facilitates the realization of full-color circularly polarized luminescence.

The diphenylalanine (FF) and its derivatives are widely studied for their self-assembly, mechanical strength, and diverse applications in materials and the biomedicine field. To develop a stable, and synthetically accessible nonpeptidic FF mimic, 14 aromatic derivatives of l-phenylalanine (A1 to A7) and l-phenylglycine (G1 to G7) were designed and synthesized to investigate the structure-property relationships. The systematic variation of aromatic groups, electronic substitution, and C-terminal protection enabled control of the intermolecular interactions. The morphological study revealed that rigid derivatives formed rod-like structures through strong π-π stacking, whereas the flexible derivatives produced fibrillar morphologies. The C-terminal modification promoted plate-like assemblies, while the electronic effects led to microplate formation. Here, the N-terminal phenylacetyl protection enhances the molecular flexibility of derivative A2, enabling it to mimic the morphological and optical behavior of FF-dipeptide while offering enhanced stability and highlighting a robust nonpeptidic platform for bioinspired nanomaterials.

Transition metal-catalyzed enantioconvergent deborylative C-C coupling of racemic alkylboronic esters represents a powerful tool to construct chiral C-C bonds given their availability, stability, and functional group tolerance. However, it is challenging, as the classic two-electron transmetalation occurs concertedly with stereoretention, hindering the enantioconvergent deborylative transformations. Herein, we report a radical strategy that enables the copper-catalyzed enantioconvergent deborylative C(sp³)-C(sp) coupling of benzylboronic esters with alkynes. The success of this strategy relies on two key elements: radical boron abstraction enables the enantioconvergent transformation by generating a prochiral radical; copper/chiral multidentate N,N,P-ligand catalyst promotes the desired pathways, ensuring chemo- and enantioselectivity. The strategy is orthogonal to the halide-based coupling, tolerating electron-rich aromatic rings, proceeding rapidly, and requiring low catalyst loading. We further demonstrate the generality by extending it to an enantioconvergent deborylative C(sp³)-C(sp²) coupling with alkenylboronic esters.

We introduce a multicomponent unitary coupled cluster (mcUCC) framework for quantum simulations of molecular systems that incorporate both electronic and nuclear quantum effects beyond the Born-Oppenheimer approximation. Using the nuclear-electronic orbital formalism, we construct mcUCC ansätze for positronium hydride and molecular hydrogen with a quantum proton, and analyze hardware requirements for different excitation truncations. To further reduce resource costs effectively, we employ the local unitary cluster Jastrow ansatz and implement it experimentally on IBM Q's Heron superconducting hardware. With the Physics-Inspired Extrapolation error mitigation protocol, the computed ground-state energies remain within chemical accuracy, consistent with the stated uncertainty level. These results provide the first demonstration of error-mitigated multicomponent correlated simulations on quantum hardware and outline a path toward scalable algorithms unifying electronic and nuclear degrees of freedom.

The vicious cycle between reactive oxygen species (ROS) burst and impaired mitochondria represents a core pathological driver in myocardial infarction (MI). Synergistically promoting ROS scavenging and enhancing mitophagy to achieve dual restoration of redox homeostasis and energy metabolism are crucial for the effective treatment of MI. To address this, we developed a biomimetic sesame cube-shaped selenium-doped Prussian blue nanozyme (SP) featuring Se⁰/Fe²⁺/Fe³⁺ active sites. By leveraging the superoxide dismutase (SOD)-like activity of the nanozyme, superoxide anions (·O₂^-) are converted into hydrogen peroxide (H₂O₂). Simultaneously, the material's catalase (CAT)-mimetic activity further decomposes the resulting H₂O₂ into oxygen (O₂) while cooperatively activating PINK1/Parkin-mediated mitophagy via selenium-enhanced electron transport. The nanozyme was subsequently integrated into a hydrogel to form the SP@Gel through dynamic Schiff base cross-linking between aldehyde-modified hyaluronic acid and amine-functionalized nanozyme. Upon injection into the infarcted myocardium, this hydrogel enables the sustained release of nanozymes. The SP@Gel exhibits excellent capabilities in promoting ROS scavenging and mitigating oxidative damage, thereby improving myocardial redox homeostasis. Furthermore, the SP@Gel enhances cardiac mitophagic flux and regulates this process via the PTEN-induced putative kinase 1 (PINK1)/Parkin/microtubule-associated protein 1 light chain 3 beta (LC3B) pathway, facilitating the restoration of mitochondrial structure and energy metabolism. These findings were further validated by metabolomics analyses. SP@Gel injection mediated remodeling of the MI microenvironment, resulting in significantly reduced infarct size, suppressed fibrosis, enhanced angiogenesis, and substantially improved cardiac function. This integrated nanozyme-hydrogel system represents a promising therapeutic strategy for MI, achieving synergistic treatment through the dual regulation of oxidative stress and mitochondrial quality control.

Polysaccharide lyase family 8 (PL8), which comprises glycosaminoglycans (GAGs) lyases, xanthan lyases, and alginate lyases, is an important family of Carbohydrate-Active Enzymes database. In this study, a PL8 family enzyme, CHa2, which can degrade GAGs and alginate, was identified. CHa2 exhibits the highest activity at 40/50 °C and pH 8.0, and the enzyme activities toward HA, CSA, CSC, CSD, CSE, alginate, polyM, and polyG are 54.6, 161.1, 204.0, 163.6, 66.1, 4.0, 4.1, and 0.3 U/mg, respectively. CHa2 degrades CS and HA to generate disaccharides and tetrasaccharides as the final products in the endolytic mode. And when degrading alginate, CHa2 prefers to catalyze the M-rich regions. Though they showed higher activity toward CS, the tetrasaccharides like ΔC-A, ΔA-A, and ΔD-A would resist the degradation of CHa2. The study of CHa2 provides a tool enzyme capable of selectively preparing specific structural functional oligosaccharides, which has potential application value in functional food, biomedical, and other fields.

The choice of structural resolution is a fundamental aspect of protein modeling, determining the balance between descriptive power and interpretability. Although atomistic simulations provide maximal detail, much of this information is redundant to understand the relevant large-scale motions and conformational states. Here, we introduce an unsupervised information-theoretic framework that determines the minimal number of atoms required to retain a maximally informative description of the configurational space sampled by a protein. This framework quantifies the informativeness of coarse-grained representations obtained by systematically decimating atomic degrees of freedom and evaluating the resulting clustering of sampled conformations. Application to molecular dynamics trajectories of dynamically diverse proteins shows that the optimal number of retained atoms scales linearly with system size, averaging about four heavy atoms per residue, remarkably consistent with the resolution of well-established coarse-grained models, such as MARTINI and SIRAH. Furthermore, the analysis shows that the optimal retained atom number depends not only on molecular size but also on the extent of conformational exploration, decreasing for systems dominated by collective motions. The proposed method establishes a general criterion to identify the minimal structural detail that preserves the essential configurational information, thereby offering a new viewpoint on the structure-dynamics-function relationship in proteins and guiding the construction of parsimonious yet informative multiscale models.