Publications by authors named "Daniel S Chan"

The cyclization of heteroatom-functionalized alkynes induced by d-transition-metal centers has traditionally been associated with the vinylidene pathway. However, recent evidence suggests that d-transition-metal centers can also activate alkynes through non-vinylidene pathways. In this study, we conducted a comprehensive experimental and theoretical investigation into the reactions between the Ru(II) complex [Ru([9]aneS3)(bpy)(OH)] and 2-alkynylanilines.

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Regular blood glucose monitoring and control is necessary for people with type 1 or advanced type 2 diabetes, yet diagnosing and treating patients with diabetes in an accurate, sustained and patient-friendly manner remains limited. Here, a glucose-responsive bifunctional nanosystem (PGOxMns) is constructed via one-pot biomineralisation of manganese dioxide with glucose oxidase and ε-poly-L-lysine. Under hyperglycaemic conditions, the cascade reactions that occur when glucose interacts with PGOxMns can trigger the production of Mn(II), which enhances the magnetic resonance imaging signal.

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The overexpression and overactivation of epidermal growth factor receptor (EGFR) are frequently observed in human cancers, including squamous cell carcinoma and adenocarcinoma. In this study, a covalent EGFR probe was developed by conjugating afatinib to an iridium(III) scaffold. Complex 1 showed enhanced luminescence in living epidermoid squamous carcinoma A431 cells compared to other cell lines, via engaging EGFR as confirmed via CETSA and knockdown experiments.

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Hepatocellular carcinoma (HCC) is a major contributor to global mortality rates, but current treatment options have limitations. Advanced theranostics are needed to effectively integrate diagnosis and therapeutic of HCC. Glycyrrhetinic acid (GA) has abundant binding sites with glycyrrhetinic acid receptors (GA-Rs) on the surface of HCC cells and has also been reported to possess ligands with mitochondrial-targeting capability but with limited efficacy.

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Glutathione -transferase is heterogeneously expressed in breast cancer cells and is therefore emerging as a potential diagnostic biomarker for studying the heterogeneity of breast cancers. However, available fluorescent probes for GSTs depend heavily on GSTs-catalyzed glutathione (GSH) nucleophilic substitution reactions, making them susceptible to interference by the high concentration of nucleophilic species in the cellular environment. Moreover, the functions of subcellular GSTs are generally overlooked due to the lack of suitable luminescence probes.

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Article Synopsis
  • Coenzyme A (CoA) is essential for life and plays a key role in metabolic processes, making its biosynthesis an attractive drug target, especially for treating Mycobacterium tuberculosis.
  • The enzyme CoaBC, a bifunctional protein, is crucial for CoA production and its depletion is lethal to M. tuberculosis.
  • Researchers have characterized the structure of CoaBC from Mycobacterium smegmatis and discovered new inhibitors that target a unique site on the CoaB enzyme, potentially leading to effective treatments for tuberculosis.
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Inosine-5'-monophosphate dehydrogenase (IMPDH) is a rate-limiting enzyme involved in nucleotide biosynthesis. Because of its critical role in purine biosynthesis, IMPDH is a drug design target for immunosuppressive, anticancer, antiviral and antimicrobial chemotherapy. In this study, we use mass spectrometry and X-ray crystallography to show that the inhibitor 6-Cl-purine ribotide forms a covalent adduct with the Cys-341 residue of Mycobacterium thermoresistibile IMPDH.

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CoaBC, part of the vital coenzyme A biosynthetic pathway in bacteria, has recently been validated as a promising antimicrobial target. In this work, we employed native ion mobility-mass spectrometry to gain structural insights into the phosphopantothenoylcysteine synthetase domain of E. coli CoaBC.

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Article Synopsis
  • A rapidly growing multidrug-resistant mycobacterial species poses a serious threat to individuals with cystic fibrosis and chronic lung diseases, leading to difficult-to-treat pulmonary infections and increased mortality rates.!* -
  • There is an urgent need for new antibiotics, with tRNA (mG37) methyltransferase (TrmD) identified as a promising target due to its role in preventing errors during protein synthesis in mycobacteria.!* -
  • Researchers used a fragment-based approach to design potent inhibitors of TrmD, with several candidates showing effective activity against multiple mycobacterial species, highlighting TrmD's potential as a target for new antimycobacterial drugs.!*
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Importance: Numerous studies have demonstrated that long-term outcomes after orthopedic trauma are associated with psychosocial and behavioral health factors evident early in the patient's recovery. Little is known about how to identify clinically actionable subgroups within this population.

Objectives: To examine whether risk and protective factors measured at 6 weeks after injury could classify individuals into risk clusters and evaluate whether these clusters explain variations in 12-month outcomes.

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Femoral neck fractures in young patients are uncommon but are often associated with surgical challenges and complications. The quality of reduction, more than time to surgery, has the most impact on optimizing outcomes and function. There is no consensus in the best fixation construct for these fractures.

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Fragment-based approaches in chemical biology and drug discovery have been widely adopted worldwide in both academia and industry. Fragment hits tend to interact weakly with their targets, necessitating the use of sensitive biophysical techniques to detect their binding. Common fragment screening techniques include differential scanning fluorimetry (DSF) and ligand-observed NMR.

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Article Synopsis
  • The study investigates how varying concentrations of DMSO affect the stability and unfolding of two proteins: avidin and Mycobacterium tuberculosis CYP142A1.
  • It was found that DMSO concentrations above 4% destabilize avidin, promoting dissociation and unfolding, while higher concentrations can stabilize CYP142A1 and protect it from losing its heme group.
  • The researchers used advanced techniques like nanoelectrospray ionization-ion mobility-mass spectrometry to assess these effects, revealing that DMSO alters the dissociation pathways and interactions of CYP142A1.
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Native nanoelectrospray ionization mass spectrometry is an underutilized technique for fragment screening. In this study, the first demonstration is provided of the use of native mass spectrometry for screening fragments against a protein-DNA interaction. EthR is a transcriptional repressor of EthA expression in Mycobacterium tuberculosis (Mtb) that reduces the efficacy of ethionamide, a second-line antitubercular drug used to combat multidrug-resistant Mtb strains.

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Objective: To determine whether multiple approaches pose an increased risk to fracture healing when compared with a standard single approach in the treatment of pilon (OTA 43C) fractures.

Design: Retrospective review of a prospective database.

Setting: Level I academic trauma center and level II community trauma center.

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Article Synopsis
  • The enzyme CYP121 is a promising drug target for combating antibiotic-resistant Mycobacterium tuberculosis, and a triazol-1-yl phenol compound was found to effectively bind to it through various biophysical tests.* -
  • After improving the binding affinity of the initial compound 100-fold, researchers deconstructed it to identify key structural features and optimize new lead compounds with enhanced properties.* -
  • By strategically adding a metal-binding element to potent scaffolds, they developed highly effective CYP121 inhibitors with exceptional selectivity, utilizing advanced techniques like X-ray crystallography for further insights into drug design.*
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CK2 is an intrinsically active protein kinase that is crucial for cellular viability. However, conventional kinase regulatory mechanisms do not apply to CK2, and its mode of regulation remains elusive. Interestingly, CK2 is known to undergo reversible ionic-strength-dependent oligomerization.

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Purpose: The purpose of this OTA-approved pilot study was to compare the clinical and functional outcomes of the knee joint after infrapatellar (IP) versus suprapatellar (SP) tibial nail insertion.

Design: Prospective, randomized.

Setting: Level I trauma center.

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Article Synopsis
  • Phenoxodiol, derived from the natural compound daidzein, is being studied as a strong anti-cancer agent specifically for hormone-dependent cancers.
  • Researchers modified phenoxodiol using various primary and secondary amines to create a variety of chemical analogues for testing.
  • The new compounds demonstrated significant anti-cancer effects on specific cancer cell lines while showing selectivity for cancer cells over normal lung cells.
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Correction for 'Virtual screening and optimization of Type II inhibitors of JAK2 from a natural product library' by Dik-Lung Ma et al., Chem. Commun.

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A new ruthenium(II) complex has been developed for detection of biomolecules. This complex is highly selective for histidine over other amino acids and has been applied to protein staining in an SDS-PAGE gel.

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CONSPECTUS: Compared with organic small molecules, metal complexes offer several distinct advantages as therapeutic agents or biomolecular probes. Carbon atoms are typically limited to linear, trigonal planar, or tetrahedral geometries, with a maximum of two enantiomers being formed if four different substituents are attached to a single carbon. In contrast, an octahedral metal center with six different substituents can display up to 30 different stereoisomers.

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We report herein the synthesis and application of a series of novel cyclometalated iridium(III) complexes 1-3 bearing a rhodamine-linked NˆN ligand for the detection of Cu(2+) ions. Under the optimised conditions, the complexes exhibited high sensitivity and selectivity for Cu(2+) ions over a panel of other metal ions, and showed consistent performance in a pH value range of 6 to 8. Furthermore, the potential application of this system for the monitoring of Cu(2+) ions in tap water or natural river water samples was demonstrated.

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We report herein the ability of exonuclease III to cleave C-Ag-C mismatched DNA, which was utilised for the construction of an exonuclease III-assisted, label-free, switch-on luminescent platform for Ag ions using a novel G-quadruplex-selective iridium(iii) complex.

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