Intramolecular CH⋯π attraction mediated conformational polymorphism of constrained helical peptides.

In nature, biochemical processes depend on polymorphism, a phenomenon by which discrete biomolecules can adopt specific conformations based on their environment. However, it is often difficult to explore the generation mechanism and achieve polymorphic control in artificial supramolecular assembly systems. In this work, we propose a feasible thought for exploring the transformation mechanism of polymorphism in peptide assembly from the perspective of thermodynamic regulation, which enables polymorphic composition to be limited by switchable intramolecular CH⋯π attraction within a certain temperature range.

A pyridinium-based strategy for lysine-selective protein modification and chemoproteomic profiling in live cells.

Protein active states are dynamically regulated by various modifications; thus, endogenous protein modification is an important tool for understanding protein functions and networks in complicated biological systems. Here we developed a new pyridinium-based approach to label lysine residues under physiological conditions that is low-toxicity, efficient, and lysine-selective. Furthermore, we performed a large-scale analysis of the ∼70% lysine-selective proteome in MCF-7 cells using activity-based protein profiling (ABPP).

β-Carbonyl sulfonium enables cysteine-specific bioconjugation for activity-based protein profiling in live cells.

Chemical labeling methods for proteins are highly researched. Herein, we introduced β-carbonyl sulfonium compounds for selective cysteine modification in proteins within biological systems. Structural tuning led to sulfonium-based probes with high reactivity and selectivity.

4-Iodine -Methylpyridinium-Mediated Peptide Synthesis.

Through systematic optimization of halopyridinium compounds, we established a peptide coupling protocol utilizing 4-iodine -methylpyridinium () for solid-phase peptide synthesis (SPPS). The coupling reagent is easily prepared, bench stable, and cost-effective. Employing in the SPPS process has showcased remarkable chemoselectivity and efficiency, effectively eliminating racemization and epimerization.

Pyridinium-Based Strategy for a Bioorthogonal Conjugation-Assisted Purification Method for Profiling Cell Surface Proteome.

Cell surface proteins (CSPs) are valuable targets for therapeutic agents, but achieving highly selective CSP enrichment in cellular physiology remains a technical challenge. To address this challenge, we propose a newly developed sulfo-pyridinium ester (SPE) cross-linking probe, followed by two-step imaging and enrichment. The SPE probe showed higher efficiency in labeling proteins than similar NHS esters at the level of cell lysates and demonstrated specificity for Lys in competitive experiments.

Covalent Peptide LSD1 Inhibitor Specifically Recognizes Cys360 in the Enzyme-Active Region.

Lysine-specific demethylase 1 (LSD1) is a promising therapeutic target, especially in cancer treatment. Despite several LSD1 inhibitors being discovered for the cofactor pocket, none are FDA-approved. We aimed to develop stabilized peptides for irreversible LSD1 binding, focusing on unique cysteine residue Cys360 in LSD1 and SNAIL1.

ConMLP: MLP-Based Self-Supervised Contrastive Learning for Skeleton Data Analysis and Action Recognition.

Human action recognition has drawn significant attention because of its importance in computer vision-based applications. Action recognition based on skeleton sequences has rapidly advanced in the last decade. Conventional deep learning-based approaches are based on extracting skeleton sequences through convolutional operations.

The thiol-sulfoxonium ylide photo-click reaction for bioconjugation.

Visible-light-mediated methods were heavily studied as a useful tool for cysteine-selective bio-conjugation; however, many current methods suffer from bio-incompatible reaction conditions and slow kinetics. To address these challenges, herein, we report a transition metal-free thiol-sulfoxonium ylide photo-click reaction that enables bioconjugation under bio-compatible conditions. The reaction is highly cysteine-selective and generally finished within minutes with naturally occurring riboflavin derivatives as organic photocatalysts.

Diversity-Oriented Synthesis of ERα Modulators via Mitsunobu Macrocyclization.

The diversity of cyclic peptides was expanded by elaborating Mitsunobu macrocyclization, tethering various hydroxy acid building blocks with different N-amine substituents. This new strategy was then applied in synthesizing peptidomimetic estrogen receptor modulator (PERM) analogs on the solid support. The PERM analogs exhibited increased serum peptidase stability, cell penetration, and estrogen receptor α binding affinity.

Novel Strategies in C-H Oxidations for Natural Product Diversification-A Remote Functionalization Application Summary.

Selectively activating the distal inactive C-H bond for functionalization is one of the on-going challenge in organic synthetic chemistry. In recent years, benefiting from the development of selective synthesis methods, novel methodologies not only make it possible to break non-traditional chemical bonds and attain more diversity in inactive sites, but also provide more possibilities for the diversification of complex natural products. Direct C-H bond functionalization approaches make it feasible to explore structure-activity relationship (SAR), generate metabolites and derivatives, and prepare biological probes.

Synthesis and Biological Evaluation of -Aminoimidazolidin-2-one-Containing Angiotensin-(1-7) Peptidomimetics.

-Aminoimidazolidin-2-one (Aid)-containing peptides with a constrained backbone present a novel class of peptidomimetics for drug discovery. The introduction of Aid residues into peptide sequences has been achieved by intramolecular Mitsunobu cyclization of a serine side chain onto the α-NH of an aza-glycine residue. The effectiveness of this new strategy was demonstrated by synthesizing six Aid-containing analogues of angiotensin-(1-7) on solid support.

Effects of exogenous Ca on stomatal traits, photosynthesis, and biomass of maize seedings under salt stress.

Understanding the responses of stomatal structure, photosynthesis and biomass of maize to exogenous Ca addition under NaCl stress has important significance for further uncovering the alleviative mechanism of exogenous Ca on maize under salt stress. We examined the effects of exogenous Ca(0, 5, 10, 20, 40, 80 mmol·L) on the stomatal structure, photosynthesis and biomass of maize (Zea mays L. cv.

Free partial latissimus dorsi myocutaneous flap for coverage of severe achilles contracture in children.

Achilles tendon and soft-tissue contractures caused by trauma to the foot and ankle are complex injuries. An array of techniques, including local and distant flaps, has been used and described to reconstruct these challenging wounds. However, the management of these injuries in a growing child who develops abnormal gait due to equinus deformity has not been categorically reported.

Synthesis of phenothiazines via ligand-free CuI-catalyzed cascade C-S and C-N coupling of aryl ortho-dihalides and ortho-aminobenzenethiols.

A ligand-free CuI-catalyzed cascade C-S and C-N cross coupling of (hetero)aryl ortho-dihalides and ortho-aminobenzenethiols has been developed, and various phenothiazines were synthesized with excellent regioselectivity. A possible mechanism is proposed for the cascade coupling.

Palladium-catalyzed C-N cross coupling of sulfinamides and aryl halides.

The palladium-catalyzed C-N cross coupling of sulfinamides and aryl halides is reported. In the presence of Pd(2)(dba)(3), tBuXPhos, NaOH, and a small amount of water, the C-N cross coupling of chiral tert-butanesulfinamide and aryl halides was accomplished to give N-aryl tert-butanesulfinamide without racemization, and the coupling of racemic p-toluenesulfinamide smoothly afforded N-aryl p-toluenesulfinamides. 2-Bromopyridine was also suitable for the coupling.

(R)-N-(3-Meth-oxy-phen-yl)-tert-butane-sulfinamide.

The title compound, C(11)H(17)NO(2)S, was obtained by the reaction of (R)-tert-butane-sulfinamide with 3-meth-oxy-phenyl bromide in toluene. In the crystal, mol-ecules inter-act head-to-tail through N-H⋯O and C-H⋯O hydrogen bonds, forming one-dimensional chains parallel to the a axis.