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Abstract Cell-penetrating peptides show promise as versatile tools for intracellular delivery of therapeutic agents. Various peptides have originated from natural proteins with antimicrobial activity. We investigated the mammalian cell-penetrating properties of a 16-residue peptide with the sequence GRCRGFRRRCFCTTHC from the C-terminus tail of the Medicago truncatula defensin MtDef4. We evaluated the peptide’s ability to penetrate multiple cell types. Our results demonstrate that the peptide efficiently penetrates mammalian cells within minutes and at a micromolar concentration. Moreover, upon N-terminal fusion to the fluorescent protein GFP, the peptide efficiently delivers GFP into the cells. Despite its remarkable cellular permeability, the peptide has only a minor effect on cellular viability, making it a promising candidate for developing a cell-penetrating peptide with potential therapeutic applications.

Methionine biosynthesis relies on the sequential catalysis of multiple enzymes. Escherichia coli, the main bacteria used in research and industry for protein production and engineering, utilizes the three-step trans-sulfurylation pathway catalyzed by L-homoserine O-succinyl transferase, cystathionine gamma synthase and cystathionine beta lyase to convert L-homoserine to L-homocysteine. However, most bacteria employ the two-step direct-sulfurylation pathway involving L-homoserine O-acetyltransferases and O-acetyl homoserine sulfhydrylase. We previously showed that a methionine-auxotroph Escherichia coli strain (MG1655) with deletion of metA, encoding for L-homoserine O-succinyl transferase, and metB, encoding for cystathionine gamma synthase, could be complemented by introducing the genes metX, encoding for L-homoserine O-acetyltransferases and metY, encoding for O-acetyl homoserine sulfhydrylase, from various sources, thus altering the Escherichia coli methionine biosynthesis metabolic pathway to direct-sulfurylation. However, introducing metX and metY from Corynebacterium glutamicum failed to complement methionine auxotrophy. Herein, we generated a randomized genetic library based on the metX and metY of Corynebacterium glutamicum and transformed it into a methionine-auxotrophic Escherichia coli strain lacking the metA and metB genes. Through multiple enrichment cycles, we successfully isolated active clones capable of growing in M9 minimal media. The dominant metX mutations in the evolved methionine-autotrophs Escherichia coli were L315P and H46R. Interestingly, we found that a metY gene encoding only the N-terminus 106 out of 438 amino acids of the wild-type MetY enzyme is functional and supports the growth of the methionine auxotroph. Recloning the new genes into the original plasmid and transforming them to methionine auxotroph Escherichia coli validated their functionality. These results show that directed enzyme-evolution enables fast and simultaneous engineering of new active variants within the Escherichia coli methionine direct-sulfurylation pathway, leading to efficient complementation.

Abstract Methionine is an essential amino acid in mammals and a precursor for vital metabolites required for the survival of all organisms. Consequently, its inclusion is required in diverse applications, such as food, feed, and pharmaceuticals. Although amino acids and other metabolites are commonly produced through microbial fermentation, high-yield biosynthesis of L-methionine remains a significant challenge due to the strict cellular regulation of the biosynthesis pathway. As a result, methionine is produced primarily synthetically, resulting in a racemic mixture of D,L-methionine. This study explores methionine bio-production in E. coli by replacing its native trans-sulfurylation pathway with the more common direct-sulfurylation pathway used by other bacteria. To this end, we generated a methionine auxotroph E. coli strain (MG1655) by simultaneously deleting metA and metB genes and complementing them with metX and metY from different bacteria. Complementation of the genetically modified E. coli with metX/metY from Cyclobacterium marinum or Deinococcus geothermalis, together with the deletion of the global repressor metJ and overexpression of the transporter yjeH, resulted in a substantial increase of up to 126 and 160-fold methionine relative to the wild-type strain, respectively, and accumulation of up to 700 mg/L using minimal MOPS medium and 2 ml culture. Our findings provide a method to study methionine biosynthesis and a chassis for enhancing L-methionine production by fermentation.

Abstract The currently employed tooth extraction methods in dentistry involve mechanical disruption of the periodontal ligament fibers, leading to inevitable trauma to the bundle bone comprising the socket walls. In our previous work, we have shown that a recombinantly expressed truncated version of clostridial collagenase G (ColG) purified from Escherichia coli efficiently reduced the force needed for tooth extraction in an ex-situ porcine jaw model, when injected into the periodontal ligament. Considering that enhanced thermostability often leads to higher enzymatic activity and to set the basis for additional rounds of optimization, we used a computational protein design approach to generate an enzyme to be more thermostable while conserving the key catalytic residues. This process generated a novel collagenase (ColG-variant) harboring sixteen mutations compared to ColG, with a nearly 4℃ increase in melting temperature. Herein, we explored the potential of ColG-variant to further decrease the physical effort required for tooth delivery using our established ex-situ porcine jaw model. An average reduction of 11% was recorded in the force applied to extract roots of mandibular split first and second premolar teeth treated with ColG-variant, relative to those treated with ColG. Our results show for the first time the potential of engineering enzyme properties for dental medicine and further contribute to minimally invasive tooth extraction.

Alpelisib plus fulvestrant is a valid second or advanced line of treatment for patients with metastatic hormone receptor (HR)-positive, HER2-negative breast cancer who harbor an activating PIK3CA mutation. The well-known side effects of alpelisib are hyperglycemia, rash, and diarrhea. Herein, we report a case of a woman who developed diffuse depigmented macules on the face, arms and legs, three months after initiating alpelisib. Both clinical and histopathological findings were consistent with new-onset vitiligo. To our knowledge, this is the first case described in literature which suggests a causal relationship between alpelisib and irreversible dermatological adverse effect.

IntroductionPathogenic variants of the junctional adhesion molecule 3 (JAM3/JAM-C; OMIM#606871) is the cause of the rare recessive disorder called hemorrhagic destruction of the brain, subependymal calcification, and cataracts (HDBSCC, OMIM#613730) disease. A similar phenotype is universal, including congenital cataracts and brain hemorrhages with high mortality rate in the first few weeks of life and with a poor neurologic outcome in survivors. We aim to describe and enlighten novel phenotype and genotype of a new patient and review the literature regarding all reported patients worldwide.Case reportWe report the case of a prenatal and postnatal phenotype of a new patient with a novel pathogenic loss-of-function variant in JAM3, who presented prenatally with cataracts and brain anomalies and postnatally with brain hemorrhages, failure to thrive (FTT), progressive microcephaly, recurrent posterior capsule opacities, and auditory neuropathy.DiscussionThis study enlightens novel possible functions of JAM3 in the normal development of the brain, the ocular lenses, the auditory system, and possibly the gastrointestinal tract. This study is the first to report of cataracts evident in as early as 23 weeks of gestation and a rare phenomenon of recurrent posterior capsule opacities despite performing recurrent posterior capsulectomy and anterior vitrectomy. We suggest that auditory neuropathy, which is reported here for the first time, is part of the phenotype of HDBSCC, probably due to an endothelial microvasculature disruption of the peripheral eighth nerve or possibly due to impaired nerve conduction from the synapse to the brainstem.ConclusionsPrenatal cataracts, brain anomalies, FTT, and auditory neuropathy are part of the phenotype of the HDBSCC disease. We suggest including JAM3 in the gene list known to cause congenital cataracts, brain hemorrhages, and hearing loss. Further studies should address the auditory neuropathy and FTT phenomena in knockout mice models. We further suggest performing comprehensive ophthalmic, audiologic, and gastroenterologic evaluations for living patients worldwide to further confirm these novel phenomena in this rare entity.

Design of peptide binders is an attractive strategy for targeting "undruggable" protein-protein interfaces. Current design protocols rely on the extraction of an initial sequence from one known protein interactor of the target protein, followed by in-silico or in-vitro mutagenesis-based optimization of its binding affinity. Wet lab protocols can explore only a minor portion of the vast sequence space and cannot efficiently screen for other desirable properties such as high specificity and low toxicity, while in-silico design requires intensive computational resources and often relies on simplified binding models. Yet, for a multivalent protein target, dozens to hundreds of natural protein partners already exist in the cellular environment. Here, we describe a peptide design protocol that harnesses this diversity via a machine learning generative model. After identifying putative natural binding fragments by literature and homology search, a compositional Restricted Boltzmann Machine is trained and sampled to yield hundreds of diverse candidate peptides. The latter are further filtered via flexible molecular docking and an in-vitro microchip-based binding assay. We validate and test our protocol on calcineurin, a calcium-dependent protein phosphatase involved in various cellular pathways in health and disease. In a single screening round, we identified multiple 16-length peptides with up to six mutations from their closest natural sequence that successfully interfere with the binding of calcineurin to its substrates. In summary, integrating protein interaction and sequence databases, generative modeling, molecular docking and interaction assays enables the discovery of novel protein-protein interaction modulators.

The COVID-19 pandemic has had direct and indirect effects on daily life. In hospitals, the impact of the pandemic was observed in the diagnostic and therapeutic workflow. In this work, we explored potential changes in activities related to the treatment of foreign body injuries (FBIs) in children and the behavioral habits of physicians during the first wave of the pandemic. An online survey was conducted among physicians of the Susy Safe network. The survey comprised items related to respondent information, reference center characteristics, the treatment of FBIs during the COVID-19 pandemic, and a modified COVID-19 Anxiety Scale (CAS). The survey was distributed among the Susy Safe project international network surveillance registry for FBIs. A total of 58 physicians responded to the survey, including 18 (32%) from Europe and 16 (28%) from South America. The respondents indicated that the estimated number of aspirated foreign bodies during the pandemic was lower than or the same as that before the pandemic (43, 74%), and the same was observed for ingested foreign bodies (43, 74%). In univariable logistic regression, no single predictor was associated with a delay in routine care for children or an increasing tendency of medical personnel to avoid procedures. The workflow of physicians involved in the management of FBIs in children has not changed drastically during the COVID-19 pandemic, especially in emergency departments.

Abstract Mortality rates among patients suffering from acute respiratory failure remain perplexingly high despite the maintenance of blood oxygen homeostasis during ventilatory support. The biotrauma hypothesis advocates that mechanical forces from invasive ventilation trigger immunological mediators that spread systemically. Yet, how these forces elicit an immune response remains unclear. Here, a biomimetic in vitro three‐dimensional (3D) upper airways model allows to recapitulate lung injury and immune responses induced during invasive mechanical ventilation in neonates. Under such ventilatory support, flow‐induced stresses injure the bronchial epithelium of the intubated airways model and directly modulate epithelial cell inflammatory cytokine secretion associated with pulmonary injury. Fluorescence microscopy and biochemical analyses reveal site‐specific susceptibility to epithelial erosion in airways from jet‐flow impaction and are linked to increases in cell apoptosis and modulated secretions of cytokines IL‐6, ‐8, and ‐10. In an effort to mitigate the onset of biotrauma, prophylactic pharmacological treatment with Montelukast, a leukotriene receptor antagonist, reduces apoptosis and pro‐inflammatory signaling during invasive ventilation of the in vitro model. This 3D airway platform points to a previously overlooked origin of lung injury and showcases translational opportunities in preclinical pulmonary research toward protective therapies and improved protocols for patient care.

ObjectiveStudies have demonstrated a potential correlation between low vitamin D status and both an increased risk of infection with SARS-CoV-2 and poorer clinical outcomes. This retrospective study examines if, and to what degree, a relationship exists between pre-infection serum 25-hydroxyvitamin D (25(OH)D) level and disease severity and mortality due to SARS-CoV-2.ParticipantsThe records of individuals admitted between April 7th, 2020 and February 4th, 2021 to the Galilee Medical Center (GMC) in Nahariya, Israel, with positive polymerase chain reaction (PCR) tests for SARS-CoV-2 (COVID-19) were searched for historical 25(OH)D levels measured 14 to 730 days prior to the positive PCR test.DesignPatients admitted to GMC with COVID-19 were categorized according to disease severity and level of 25(OH)D. An association between pre-infection 25(OH)D levels, divided between four categories (deficient, insufficient, adequate, and high-normal), and COVID-19 severity was ascertained utilizing a multivariable regression analysis. To isolate the possible influence of the sinusoidal pattern of seasonal 25(OH)D changes throughout the year, a cosinor model was used.ResultsOf 1176 patients admitted, 253 had records of a 25(OH)D level prior to COVID-19 infection. A lower vitamin D status was more common in patients with the severe or critical disease (ConclusionsAmong hospitalized COVID-19 patients, pre-infection deficiency of vitamin D was associated with increased disease severity and mortality.

Inverting seismic data to build 3D geological structures is a challenging task due to the overwhelming amount of acquired seismic data, and the very-high computational load due to iterative numerical solutions of the wave equation, as required by industry-standard tools such as Full Waveform Inversion (FWI). For example, in an area with surface dimensions of 4.5 km × 4.5 km, hundreds of seismic shot-gather cubes are required for 3D model reconstruction, leading to Terabytes of recorded data. This paper presents a deep learning solution for the reconstruction of realistic 3D models in the presence of field noise recorded in seismic surveys. We implement and analyze a convolutional encoder–decoder architecture that efficiently processes the entire collection of hundreds of seismic shot-gather cubes. The proposed solution demonstrates that realistic 3D models can be reconstructed with a structural similarity index measure (SSIM) of 0.9143 (out of 1.0) in the presence of field noise at 10 dB signal-to-noise ratio.

Minimally invasive exodontia is among the long-sought-for development aims of safe dental medicine. In this paper, we aim, for the first time, to examine whether the enzymatic disruption of the periodontal ligament fibers reduces the force required for tooth extraction. To this end, recombinantly expressed clostridial collagenase G variant purified from Escherichia coli was injected into the periodontal ligament of mesial and distal roots of the first and second split porcine mandibular premolars. The vehicle solution was injected into the corresponding roots on the contralateral side. Following sixteen hours, the treated mandibles were mounted on a loading machine to measure the extraction force. In addition, the effect of the enzyme on the viability of different cell types was evaluated. An average reduction of 20% in the applied force (albeit with a large variability of 50 to 370 newton) was observed for the enzymatically treated roots, reaching up to 50% reduction in some cases. Importantly, the enzyme showed only a minor and transient effect on cellular viability, without any signs of toxicity. Using an innovative model enabling the analytical measurement of extraction forces, we show, for the first time, that the enzymatic disruption of periodontal ligament fibers substantially reduces the force required for tooth extraction. This novel technique brings us closer to atraumatic exodontia, potentially reducing intra- and post-operative complications and facilitating subsequent implant placement. The development of novel enzymes with enhanced activity may further simplify the tooth extraction process and present additional clinical relevance for the broad range of implications in the oral cavity.

The initial discovery phase of protein modulators, which consists of filtering molecular libraries and in vitro direct binding validation, is central in drug discovery. Thus, virtual screening of large molecular libraries, together with the evaluation of binding affinity by isothermal calorimetry, generates an efficient experimental setup. Herein, we applied virtual screening for discovering small molecule inhibitors of MDM2, a major negative regulator of the tumor suppressor p53, and thus a promising therapeutic target. A library of 20 million small molecules was screened against an averaged model derived from multiple structural conformations of MDM2 based on published structures. Selected molecules originating from the computational filtering were tested in vitro for their direct binding to MDM2 via isothermal titration calorimetry. Three new molecules, representing distinct chemical scaffolds, showed binding to MDM2. These were further evaluated by exploring structure-similar chemical analogues. Two scaffolds were further evaluated by de novo synthesis of molecules derived from the initial molecules that bound MDM2, one with a central oxoazetidine acetamide and one with benzene sulfonamide. Several molecules derived from these scaffolds increased wild-type p53 activity in MCF7 cancer cells. These set a basis for further chemical optimization and the development of new chemical entities as anticancer drugs.

Extraskeletal Ewing’s sarcoma is a rare tumor, and the management of airway compromise in case of cervical Ewing’s sarcoma has not been established. This report describes the case of a patient with retrotracheal Ewing’s sarcoma and discusses a successful approach to airway management. A 12-year-old male presented with a 2-week history of sore throat and sleep-disordered breathing and 48 hours of stridor. Imaging confirmed a retrotracheal soft tissue mass with airway compromise. A planned and controlled approach to his airway management resulted in a secure airway prior to definitive treatment.

The title compound, [Cs(CH3COO)(C28H16O8)(C2H5OH)]·C2H5OH, is the product of the complexation between one vasarene analogue [1], bis ninhydrin naphthalene-1,3-diol and CsF, where the F− ion has reacted with residual acetic acid (AcOH), to form a [1]·CsOAc complex. The intermolecular interactions with the multiple oxygen-containing functional groups of the ligand, as well as O—H...O hydrogen bonds involving the ethanol solvent molecules, stabilize the complex, forming a chain along [100]. Additional parallel-displaced π–π stacking, with an interplanar distance of 3.669 (1) Å, connect several unit cells in a three-dimensional supramolecular structure, though, the larger size of AcO− (1.60 Å) compared to F− (1.33 Å) prevents the tight packing that was once achieved with other vasarene complexes of CsF.

The reaction between bis-ninhydrin resorcinol and benzyltrimethylammonium fluoride in ethanol has produced the title compound, 2C10H16N+·2C24H13O8−·1.5H2O, which contains a unique centrosymmetric supramolecular dimeric entity, where two deprotonated ligands are held together via two strong and short [O...O = 2.4395 (13) Å] [O—H—O]− bonds of the type negative charge-assisted hydrogen bonds (–CAHB). The central aromatic rings of the ligands create parallel-displaced π–π stacking at an interplanar distance of 3.381 (1) Å, which helps stabilize the dimer. In the crystal, two symmetry-related solvent water molecules with a site occupancy of 0.75 are attached to the carbonyl groups of the dimer by weaker O—H...O hydrogen bonds, forming chains along [101].

The title compound, C15H12N4O11·5H2O, has a `propeller-like' structure. The two alloxan units have screw-boat conformations. Their mean planes are normal to the central aromatic ring with dihedral angles of 87.91 (7) and 88.27 (7)°, and they are inclined to one another by 40.86 (7)°. In the crystal, molecules are linked via O—H...O and N—H...O hydrogen bonds, forming a three-dimensional framework. There are also C—H...O hydrogen bonds present within the framework.

The title compound, C24H14O9·2CH3OH, displays a chair-shaped form. The two dihydroindenone ring systems are located above and below the central fused-ring system, the dihedral angles between the mean planes of dihydroindenone ring systems and the mean plane of central fused-ring system are 67.91 (5) and 73.52 (4)°, respectively. In the crystal, extensive O—H...O hydrogen bonds, weak C—H...O hydrogen bonds and C—H...π interactions link the molecules into a three-dimensional supramolecular architecture.

Objectives. To describe the characteristics and outcome of vertigo in a pediatric population. Patients. All children and adolescents presenting with vertigo to a tertiary otoneurology clinic between the years 2003–2010 were included in the study. Results. Thirty-seven patients with a mean age of 14 years were evaluated. The most common etiology was migraine-associated vertigo (MAV) followed by acute labyrinthitis/neuritis and psychogenic dizziness. Ten patients (27%) had pathological findings on the otoneurological examination. Abnormal findings were documented in sixteen of the twenty-three (70%) completed electronystagmography evaluations. Twenty patients (54%) were referred to treatment by other disciplines than otology/otoneurology. A follow-up questionnaire was filled by twenty six (70%) of the study participants. While all patients diagnosed with MAV had continuous symptoms, most other patients had complete resolution. Conclusions. Various etiologies of vertigo may present with similar symptoms and signs in the pediatric patient. Yet, variable clinical courses should be anticipated, depending on the specific etiology. This is the reason why treatment and follow up should be specifically tailored for each case according to the diagnosis. Close collaboration with other medical disciplines is often required to reach the correct diagnosis and treatment while avoiding unnecessary laboratory examinations.

A dinuclear Cu-peptoid, Cu 2 ( BDiE ) 2 , having a diol side chain was developed as a homogeneous electrocatalyst for oxygen evolution reaction (OER) at neutral pH. The molecular structure of Cu 2 ( BDiE ) 2 was characterized and concluded by ESI-MS, UV-vis, and single-crystal X-ray diffraction. Electrochemical, spectroscopic, and mechanistic studies revealed that borate buffer (the solution medium) has a minor effect during electrocatalysis; however, the diol side chain promotes a second coordination sphere effect via multiple hydrogen bonds which highly stabilize the complex, leading to an OER. Based on these observations and the collected data, we also suggest two different and unique mechanism pathways: a major one, which involves interactions of radical intermediates, which is buffer independent, and a minor one that resembles water nucleophilic attack (WNA) and is assisted by the borate buffer.

The formation of reactive oxygen species (ROS) in the brain is a major cause of neuropathologic degradation associated with Alzheimer's Disease (AD). It has been suggested that the copper (Cu)-amyloid-β (Aβ) peptide complex can lead to ROS formation in the brain. An external chelator for Cu that can extract Cu from the CuAβ complex should inhibit the formation of ROS, making Cu chelation an excellent therapeutic approach for AD. Such a chelator should possess high selectivity for Cu over zinc (Zn), which is also present within the synaptic cleft. However, such selectivity is generally hard to achieve in one molecule due to the similarities in the binding preferences of these two metal ions. As an alternative to monotherapy (where Cu extraction is performed using a single chelator), herein we describe a variation of combination therapy - a novel cocktail approach, which is based on the co-administration of two structurally different peptidomimetic chelators, aiming to target both Cu 2+ and Zn 2+ ions simultaneously but independently from each other. Based on rigorous spectroscopic experiments, we demonstrate that our peptidomimetic cocktail allows, for the first time, the complete and immediate inhibition of ROS production by the CuAβ complex in the presence of Zn 2+ . In addition, we further demonstrate the high stability of the cocktail under simulated physiological conditions and its resistance to proteolytic degradation by trypsin and report the water/ n -octanol partition coefficient, initially assessing the blood-brain barrier (BBB) permeability potential of the chelators., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Studies on a series of molecular dicopper peptoid complexes showed that the Cu···Cu distances measured in X-ray single-crystal diffraction are typically in the range of 4.2-6.9 Å. Herein, we designed a new peptoid, L1 , having 2,2'-bipyridine, propyl, and pyridyl side chains and discovered that although it forms a typical dicopper self-assembled structure (complex 1 ), the Cu···Cu distance is exceedingly long -8.043 Å. By analyzing its structure and surface properties in comparison to a control Cu-peptoid complex ( 2 ), in which the pyridyl side chain is modified by an ethanolic side chain, we suggest that the long Cu···Cu distance is contributed by the hydrophilic-hydrophobic interaction influenced by the pyridyl side chain and the steric hindrance of the propyl side chain. This result may motivate the use of dinuclear Cu peptoid complexes for wider applications, such as cooperative catalysis and luminescence., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Water electrolysis is the simplest way to produce hydrogen, as a clean renewable fuel. However, the high overpotential and slow kinetics hamper its applicability. Designing efficient and stable electrocatalysts for water oxidation (WO), which is the first and limiting step of the water splitting process, can overcome this limitation. However, the development of such catalysts based on non-precious metal ions is still challenging. Herein we describe a bio-inspired Co(iii)-based complex i.e. , a stable and efficient molecular electrocatalyst for WO, constructed from a peptidomimetic oligomer called peptoid - N -substituted glycine oligomer - bearing two binding ligands, terpyridine and bipyridine, and one ethanolic group as a proton shuttler. Upon binding of a cobalt ion, this peptoid forms an intramolecular Co(iii) complex, that acts as an efficient electrocatalyst for homogeneous WO in aqueous phosphate buffer at pH 7 with a high faradaic efficiency of up to 92% at an overpotential of about 430 mV, which is the lowest reported for Co-based homogeneous WO electrocatalysts to date. We demonstrated the high stability of the complex during electrocatalytic WO and that the ethanolic side chain plays a key role in the stability and activity of the complex and also in facilitating water binding, thus mimicking an enzymatic second coordination sphere., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Copper is an essential metal ion that is involved in critical cellular processes, but which can also exhibit toxic effects through its ability to catalyze reactive oxygen species (ROS) formation. Dysregulation of copper homeostasis has been implicated in the progression of several diseases, including cancer. A novel therapeutic approach, extensively studied in recent years, is to capitalize on the increased copper uptake and dependency exhibited by cancer cells and to promote copper-associated ROS production within the tumor microenvironment, leading to the apoptosis of cancer cells. Such an effect can be achieved by selectively chelating copper from copper-bearing metalloproteins in cancer cells, thereby forming a copper-chelator complex that produces ROS and, through this, induces oxidative stress and initiates apoptosis. Herein, we describe a peptoid chelator, TB , that is highly suitable to carry this task. Peptoids are N-substituted glycine oligomers that can be efficiently synthesized on a solid support and are also biocompatible; thus, they are considered promising drug candidates. We show, by rigorous spectroscopic techniques, that TB is not only selective for Cu(II) ions, but can also effectively extract copper from metallothionein-2, and the formed complex Cu TB can promote ROS production. Our findings present a promising first example for the future development of peptoid-based chelators for applications in anti-cancer chelation therapy, highlighting the potential for the prospect of peptoid chelators as therapeutics.

Stabilization of Cu(I) is ubiquitous within native copper proteins. Understanding how to stabilize Cu(I) within synthetic biomimetic systems is therefore desired towards biological applications. Peptoids are an important class of peptodomimetics, that can bind metal ions and stabilize them in their high oxidation state. Thus, to date, they were not used for Cu(I) binding. Here we show how the helical peptoid hexamer, having two 2,2'-bipyridine (Bipy) groups that face the same side of the helix, forms the intramolecular air stable Cu(I) complex. Further study of the binding site by rigorous spectroscopic techniques suggests that Cu(I) is tetracoordinated, binding to only three N atoms from the Bipy ligands and to the N-terminus of the peptoid's backbone. A set of control peptoids and experiments indicates that the Cu(I) stability and selectivity are dictated by the intramolecular binding, forced by the helicity of the peptoid, which can be defined as the second coordination sphere of the metal center., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Borate buffer was found to have both structural and functional roles within a low-cost tri-copper electrocatalyst for homogeneous water oxidation that exhibits a high turnover frequency of 310 s -1 . The borate buffer was shown to facilitate the catalytic activity by both bridging the three Cu ions and participating in O-O bond formation. Phosphate and acetate buffers did not show such roles, making borate a unique player in this catalytic system., (© 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Incorporating a chiral non-coordinating substitution at the N-terminal end within peptoids facilitates regio-selective amide bond hydrolysis mediated by a transition metal ion and/or an acidic buffer as evident by X-ray crystallographic analysis, supported by ESI-MS. This opens up a new direction for peptidomimetic compounds towards future application in chemistry, biology and medicine.

Cu bound to amyloid-β (Aβ) peptides can act as a catalyst for the formation of reactive oxygen species (ROS), leading to neuropathologic degradation associated with Alzheimer's disease (AD). An excellent therapeutic approach is to use a chelator that can selectively remove Cu from Cu-Aβ. This chelator should compete with Zn 2+ ions (Zn) that are present in the synaptic cleft while forming a nontoxic Cu complex. Herein we describe P3, a water-soluble peptidomimetic chelator that selectively removes Cu 2+ from Cu-Aβ in the presence of Zn and prevent the formation of ROS even in a reductive environment. We demonstrate, based on extensive spectroscopic analysis, that although P3 extracts Zn from Cu,Zn-Aβ faster than it removes Cu, the formed Zn complexes are kinetic products that further dissociate, while CuP3 is formed as an exclusive stable thermodynamic product. Our unique findings, combined with the bioavailability of peptoids, make P3 an excellent drug candidate in the context of AD., (© 2021 Wiley-VCH GmbH.)

Water electrolysis is a promising approach toward low-cost renewable fuels; however, the high overpotential and slow kinetics limit its applicability. Studies suggest that either dinuclear copper (Cu) centers or the use of borate buffer can lead to efficient catalysis. We previously demonstrated the ability of peptoids-N-substituted glycine oligomers-to stabilize high-oxidation-state metal ions and to form self-assembled di-copper-peptoid complexes. Capitalizing on these features herein we report on a unique Cu-peptoid duplex, Cu 2 ( BEE ) 2 , that is a fast and stable homogeneous electrocatalyst for water oxidation in borate buffer at pH 9.35, with low overpotential and a high turnover frequency of 129 s -1 (peak current measurements) or 5503 s -1 (FOWA); both are the highest reported for Cu-based water electrocatalysts to date. BEE is a peptoid trimer having one 2,2'-bipyridine ligand and two ethanolic groups, easily synthesized on solid support. Cu 2 ( BEE ) 2 was characterized by single-crystal X-ray diffraction and various spectroscopic and electrochemical techniques, demonstrating its ability to maintain stable in four cycles of controlled potential electrolysis, leading to a high overall turnover number of 51.4 in a total of 2 h. Interestingly, the catalytic activity of control complexes having only one ethanolic side chain is 2 orders of magnitude lower than that of Cu 2 ( BEE ) 2 . On the basis of this comparison and on mechanistic studies, we propose that the ethanolic side chains and the borate buffer have significant roles in the high stability and catalytic activity of Cu 2 ( BEE ) 2 ; the -OH groups facilitate protons transfer, while the borate species enables oxygen transfer toward O-O bond formation.

The design of a stimuli-responsive peptide whose conformation is controlled by wavelength-specific light and metal coordination is described. The peptide adopts a defined tertiary structure and its conformation can be modulated between an α-helical coiled coil and β-sheet. The peptide is designed with a hydrophobic interface to induce coiled coil formation and is based on a recently described strategy to obtain switchable helix dimers. Herein, we endowed the helix dimer with 8-hydroxyquinoline (HQ) groups to achieve metal coordination and shift to a β-sheet structure. It was found that the conformational shift only occurs upon introduction of Zn 2+ ; other metal ions (Cu 2+ , Fe 3+ , Co 2+ , Mg 2 , and Ni 2+ ) do not offer switching likely due to non-specific metal-peptide coordination. A control peptide lacking the metal-coordinating residues does not show conformational switching with Zn 2+ supporting the role of this metal in stabilizing the β-sheet conformation in a defined manner., (© 2021 Wiley-VCH GmbH.)

The formidable reactivity of the oxygen-evolving center near photosystem II is largely based on its protein environment that stabilizes it during catalysis. Inspired by this concept, the water-soluble Mn 12 clusters Mn 12 O 12 (O 2 CC 6 H 3 (OH) 2 ) 16 (H 2 O) 4 (3,5DHMn 12 ) and Mn 12 O 12 (O 2 CC 6 H 3 (OH) 3 ) 16 (H 2 O) 4 (3,4,5THMn 12 ) were developed as efficient electrocatalysts for water oxidation. In this work, the role of the -OH groups in the electrocatalytic process was explored by describing the structural and electrocatalytic properties of two new Mn 12 clusters, 3,4DHMn 12 and 2,3DHMn 12 , having one -OH group in the meta position relative to the benzoate-Mn moiety, and one at the para or ortho position, respectively. The Mn centers in 3,4DHMn 12 were discovered to have lower oxidation potential compared with those in 2,3DHMn 12 , and thus, 3,4DHMn 12 can catalyze water oxidation with higher rate and TON than 2,3DHMn 12 . Hence, the role of the -OH groups in the electrocatalysis was established, being involved in electronic stabilization of the Mn centers or in proton shuttling., (© 2021 Wiley-VCH GmbH.)

Chelation of Cu 2+ by synthetic molecules is an emerging therapeutic approach for treating several illnesses in human body such as Wilson disease, cancer and more. Among synthetic metal chelators, those based on peptoids - N-substituted glycine oligomers - are advantageous due to their structural similarity to peptides, ease of synthesis on solid support and versatile controlled sequences. Tuning peptoid sequences, via systematically changing at least one side chain, can facilitate and control their function. Along these lines, this work aims to explore the role of the non-coordinating side chain within peptoid chelators in order to understand the factors that control the selectivity of these chelators to Cu 2+ in water medium. To this aim, a set of peptoid trimers having a pyridine group at the acetylated N-terminal, a 2,2'-bipyridine group at the second position and a non-coordinating group at the C-terminus, where the latter is systematically varied between aromatic, aliphatic, chiral or non-chiral, were investigated as selective chelators for Cu 2+ . The effect of the position of the non-coordinating group on the selectivity of the peptoid to Cu 2+ was also tested. Based on extensive spectroscopic data, we found that the choice of the non-coordinating group along with its position dramatically influences the selectivity of the peptoids to Cu 2+ . We showed that peptoids having bulky chiral groups at the C-terminus enable high selectivity to Cu 2+ . We further demonstrated the ability of one of the selective chelators to remove Cu 2+ from the natural copper binding protein metallothionein in HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) buffer medium., (Copyright © 2021 Elsevier Inc. All rights reserved.)

A peptoid trimer incorporating terpyridine and ethanol forms an intermolecular cobalt(iii) complex, which performs as a soluble electrocatalyst for water oxidation with a minimal overpotential of 350 mV and a high turnover frequency of 108 s-1. The ethanolic group facilitates water binding thus mimicking an enzymatic second coordination sphere.

Selective binding of Cu 2+ in water medium by a synthetic chelator is a promising therapeutic approach towards the treatment of various diseases including cancer. Chelation of Cu 2+ is well exercised, however water-soluble synthetic chelators that can selectively bind Cu 2+ from a pool of competing metal ions at very high excess and/or can extract Cu 2+ from a protein are hardly reported. Herein we describe the design and synthesis of an acetylated peptoid-N-substituted glycine trimer-that incorporates a picolyl group at the N-terminal, a non-coordinating but structurally directing bulky chiral phenylethyl group at the C-terminus and a modified 2,2'-bipyridine group (PCA-Nspe), which selectively binds Cu 2+ to form a water-soluble complex. We further demonstrate that the selectivity of PCA-Nspe to Cu 2+ is thermodynamically driven, leading to specific binding of Cu 2+ in an aqueous solution containing up to 60-fold excess of other biologically relevant metal ions such as Zn 2+ , Co 2+ , Mn 2+ , Ca 2+ , Mg 2+ , K + and Na + . Based on spectroscopic data and DFT calculations of PCA-Nspe as well as of a control peptoid having an achiral benzyl group instead of the phenylethyl side chain, we could suggest that the chiral and bulkier phenylethyl group at the C-terminus controls the preorganization of the two ligands, and this might play a role in the selectivity of PCA-Nspe. Significantly, we show that PCA-Nspe can extract Cu 2+ from the natural copper binding protein metallothionein., (© 2020 Wiley-VCH GmbH.)

The construction of synthetic protein mimics is a central goal in chemistry. A known approach for achieving this goal is the self-assembly of synthetic biomimetic sequences into supramolecular structures. Obtaining different 3D structures via a simple sequence modification, however, is still challenging. Herein we present the design and synthesis of biomimetic architectures, via the self-assembly of distinct copper-peptoid duplexes. We demonstrate that changing only one non-coordinating side-chain within the peptoids-sequence-specific N-substituted glycine oligomers-leads to different supramolecular structures. Four peptoid trimers incorporating 2,2'-bipyridine and pyridine ligands, and a non-coordinating but rather a structure-directed bulky group were synthesized, and their solutions were treated with Cu 2+ in a 1:1 ratio. Single-crystal X-ray analysis of the products revealed the self-assembly of each peptoid into a metallopeptoid duplex, followed by the self-assembly of multiple duplexes and their packing into a three-dimensional supramolecular architecture via hydrogen bonding and π-π interactions. Tuning the non-coordinating side-chain enables to regulate both the final structure being either a tightly packed helical rod or a nano-channel, and the pore width of the nano-channels. Importantly, all the metallopeptoids structures are stable in aqueous solution as verified by cryo-TEM measurements and supported by UV/Vis and EPR spectroscopies and by ESI-MS analysis. Thus, we could also demonstrate the selective recognition abilities of the nano-channels towards glycerol., (© 2020 Wiley-VCH GmbH.)

The selective removal of Zn 2+ from proteins by using a synthetic chelator is a promising therapeutic approach for the treatment of various diseases including cancer. Although the chelation of Zn 2+ is well known, its removal from a protein in the presence of potential competing biologically relevant ions such as Cu 2+ is hardly explored. Herein we present a peptoid - N-substituted glycine trimer - incorporating a picolyl group at the N-terminus, a non-coordinating but structurally directing benzyl group at the C-terminus and a 2,2':6',2''-terpyridine group in the second position, that selectively binds Zn 2+ ions in the presence of excess Cu 2+ ions in water. We further demonstrate that this chelator can selectively bind Zn 2+ from a pool of excess biologically relevant and competitive ions (Cu 2+ , Fe 3+ , Ca 2+ , Mg 2+ , Na + , and K + ) in a simulated body fluid (SBF), and also its ability to remove Zn 2+ from a natural zinc protein domain (PYK C PE C GKSFSQKSDLVK H QRT H TG) in a SBF., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Peptoids, N-substituted glycine oligomers, represent an important class of peptidomimetics that can fold into three-dimensional structures in solution. Most of the folded peptoid structures, however, resemble helices, and this can limit their applications, specifically in asymmetric catalysis. In this work, for the first time, unique examples of pyrrolidine-based β-turn-like peptoids are described and characterized, both in the solid state, by single-crystal X-ray analysis, and in solution, by circular dichroism spectroscopy. Furthermore, their highly efficient and enantioselective catalytic activity for the production of γ-nitro aldehydes by asymmetric Michael reaction in water was demonstrated. The structural properties and DFT-D3 calculations of the new β-turn-like peptoids, as well as catalytic and spectroscopic studies on designed pyrrolidine-based helical peptoids, suggest that the β-turn structure plays a key role in the stereoselectivity of the catalytic reaction., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A practical synthesis of preorganized tripodal enterobactin/corynebactin-type ligands (consisting of a C 3 -symmetric macrocyclic peptoid core, three catecholamide coordinating units, and C 2 , C 4 , and C 6 spacers) is reported. The formation of complexes with Fe 3+ was investigated by spectrophotometric (UV-Vis) and spectrometric (ESI, negative ionization mode) methods and corroborated by theoretical (DFT) calculations. Preliminary studies revealed the intricate interplay between the conformational chirality of cyclic trimeric peptoids and metal coordination geometry of mononuclear species similar to that of natural catechol-based siderophores. Experimental results demonstrated the unexpected formation of unique dinuclear Fe 3+ complexes.

The understanding of structure-function relationships within synthetic biomimetic systems is a fundamental challenge in chemistry. Herein we report the direct correlation between the structure of short peptoid ligands-N-substituted glycine oligomers incorporating 2,2'-bipyridine groups-varied in their monomer sequence, and the photoluminescence of Ru II centers coordinated by these ligands. Based on circular dichroism and fluorescence spectroscopy we demonstrate that while helical peptoids do not affect the fluorescence of the embedded Ru II chromophore, unstructured peptoids lead to its significant decay. Transmittance electron microscopy (TEM) revealed significant differences in the arrangements of metal-bound helical versus unstructured peptoids, suggesting that only the latter can have through-space interactions with the ruthenium dye leading to its quenching. High-resolution TEM enabled the remarkable direct imaging of singular ruthenium-bound peptoids and bundles, supporting our explanation for structure-depended quenching. Moreover, this correlation allowed us to fine-tune the luminescence properties of the complexes simply by modifying the sequence of their peptoid ligands. Finally, we also describe the chiral properties of these Ru-peptoids and demonstrate that remote chiral induction from the peptoids backbone to the ruthenium center is only possible when the peptoids are both chiral and helical., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Water electrolysis is among the simplest method for generating hydrogen as an alternative renewable fuel. A major challenge associated with this process is the development of cheap, simple, and environmentally benign catalysts that lead to a minimum overpotential for water oxidation. Inspired by the Mn 4 CaO x cluster that catalyzes water oxidation in photosystem II, described here is the synthesis and characterization of the manganese cluster [Mn 12 O 12 (O 2 CC 6 H 2 (OH) 3 ) 16 (H 2 O) 4 ] (Mn 12 TH) along with its electrocatalytic activity at pH 6. Electrochemical, spectroscopic, and electron microscopy studies show that Mn 12 TH is a homogeneous electrocatalyst for water oxidation and enables oxygen evolution with a reaction rate of 22 s -1 , high Faradic efficiency (93 %), and an overpotential of only 74 mV, the lowest reported to date. Based on the electrochemical data, the organic ligands, which can be described as the second coordination sphere of the catalytic manganese core, play a key role in facilitating the oxidation process and accelerating the reaction., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report a unique example of Ag(0) nanoparticles (NPs)-assemblies stabilized by 2,2-bipyridine (BP), via the incorporation of BP at the N-terminus of a peptoid heptamer bearing phenylethyl groups in the other positions. We show that this peptoid mediates the aggregation of the Ag(0) NPs into nanochain-like assemblies. Transmission electron microscopy, supported by UV-Vis spectroscopy analysis, revealed pre-assembly of the BP-peptoid oligomers into elongated pearl-like morphology, which serve as a template for the NPs. The fact that completely synthetic biomimetic oligomers can template and control the assembly of metal NPs, and specifically Ag(0), represents a conceptual mimic of the interaction between biomolecules and minerals for the production of nanostructured inorganic materials with complex morphologies., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Helices are key structural features in biopolymers, enabling a variety of biological functions. Mimicking these secondary structure motifs has wide potential in the development of biomimetic materials. Peptoids, N -substituted glycine oligomers, are an important class of peptide mimics that can adopt polyproline type helices if the majority of their sequence consists of chiral bulky pendent groups. Such side-chains are structure inducers but they have no functional value. We present here the inclusion of several metal-binding groups in one peptoid oligomer as a new platform towards the development of functional helical peptoids. Thus, we describe the coordination of two metal ions to unstructured peptoids incorporating four 8-hydroxyquinoline (HQ) ligands at fixed positions as two (HQ, HQ) metal binding sites, and a mixture of chiral benzyl and alkyl substituents in varied positions along the peptoid backbone. For the first time, we demonstrate by circular dichroism spectroscopy, solution NMR techniques and high-level DFT calculations that some of these unstructured peptoids can fold upon metal binding to form helical structures. Replacing one HQ ligand with a terpyridine (Terpy) ligand resulted in unique sequences that can selectively coordinate Cu 2+ to the (Terpy, HQ) and Zn 2+ (or Co 2+ ) to the (HQ, HQ) sites from a solution mixture containing Cu 2+ and Zn 2+ (or Co 2+ ) ions. Interestingly, the binding of Cu 2+ to the (Terpy, HQ) site in one of these peptoids can initiate a conformational change that in turn facilitates the coordination of Zn 2+ (or Co 2+ ) ions to the (HQ, HQ) site, demonstrating a unique example of positive allosteric cooperativity in peptide mimics.

Helical peptoids bearing 2,2'-bipyridine, varied in their chiral bulky side chains and their N-terminus form complexes with Cu(ii), Co(ii) and Ni(ii) via intramolecular binding. Chiral induction from the peptoid to each metal center could be only observed in some cases and is dependent on the identity of the N-terminus and on its position relative to the metal center.