The development of singlet oxygen photosensitizers, which target specific cellular organelles, constitutes a pertinent endeavor to optimize the efficiency of photodynamic therapy. Targeting of the cell membrane eliminates the need for endocytosis of drugs that can lead to toxicity, intracellular degradation, or drug resistance. In this context, we utilized copper-free click chemistry to prepare a singlet oxygen photosensitizing complex, made of a molybdenum-iodine nanocluster stabilized by triazolate apical ligands. In phosphate-buffered saline, the complex formed nanoaggregates with a positive surface charge due to the protonatable amine function of the apical ligands. These nanoaggregates targeted cell membranes and caused an eminent blue-light phototoxic effect against HeLa cells at nanomolar concentrations, inducing apoptotic cell death, while having no dark toxicity at physiologically relevant concentrations. The properties of this complex were compared to those of a negatively charged parent complex to highlight the dominant effect of the nature of apical ligands on biological properties of the nanocluster. These two complexes also exerted (photo)antibacterial effects on several pathogenic strains in the form of planktonic cultures and biofilms. Overall, we demonstrated that the rational design of apical ligands toward cell membrane targeting leads to enhanced photodynamic efficiency.
- MeSH
- Cell Membrane MeSH
- HeLa Cells MeSH
- Iodine * pharmacology MeSH
- Humans MeSH
- Ligands MeSH
- Molybdenum * pharmacology MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
Purpose: Plasmonic photothermal cancer therapy by gold nanorods (GNRs) emerges as a promising tool for cancer treatment. The goal of this study was to design cationic oligoethylene glycol (OEG) compounds varying in hydrophobicity and molecular electrostatic potential as ligand shells of GNRs. Three series of ligands with different length of OEG chain (ethylene glycol units = 3, 4, 5) and variants of quaternary ammonium salts (QAS) as terminal functional group were synthesized and compared to a prototypical quaternary ammonium ligand with alkyl chain - (16-mercaptohexadecyl)trimethylammonium bromide (MTAB). Methods: Step-by-step research approach starting with the preparation of compounds characterized by NMR and HRMS spectra, GNRs ligand exchange evaluation through characterization of cytotoxicity and GNRs cellular uptake was used. A method quantifying the reshaping of GNRs was applied to determine the effect of ligand structure on the heat transport from GNRs under fs-laser irradiation. Results: Fourteen out of 18 synthesized OEG compounds successfully stabilized GNRs in the water. The colloidal stability of prepared GNRs in the cell culture medium decreased with the number of OEG units. In contrast, the cellular uptake of OEG+GNRs by HeLa cells increased with the length of OEG chain while the structure of the QAS group showed a minor role. Compared to MTAB, more hydrophilic OEG compounds exhibited nearly two order of magnitude lower cytotoxicity in free state and provided efficient cellular uptake of GNRs close to the level of MTAB. Regarding photothermal properties, OEG compounds evoked the photothermal reshaping of GNRs at lower peak fluence (14.8 mJ/cm2) of femtosecond laser irradiation than the alkanethiol MTAB. Conclusion: OEG+GNRs appear to be optimal for clinical applications with systemic administration of NPs not-requiring irradiation at high laser intensity such as drug delivery and photothermal therapy inducing apoptosis.
- MeSH
- Biological Transport MeSH
- HeLa Cells MeSH
- Hydrophobic and Hydrophilic Interactions MeSH
- Colloids MeSH
- Quaternary Ammonium Compounds chemistry MeSH
- Humans MeSH
- Ligands MeSH
- Nanotubes chemistry MeSH
- Polyethylene Glycols chemistry MeSH
- Drug Stability MeSH
- Temperature * MeSH
- Gold chemistry metabolism MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
The crystal structure of an efficient Diels-Alder antibody catalyst at 1.9 angstrom resolution reveals almost perfect shape complementarity with its transition state analog. Comparison with highly related progesterone and Diels-Alderase antibodies that arose from the same primordial germ line template shows the relatively subtle mutational steps that were able to evolve both structural complementarity and catalytic efficiency.
- MeSH
- Chemical Phenomena MeSH
- Chemistry, Physical MeSH
- Templates, Genetic MeSH
- Haptens chemistry metabolism MeSH
- Immunoglobulin Fab Fragments chemistry metabolism MeSH
- Antibodies, Catalytic chemistry genetics metabolism MeSH
- Catalysis MeSH
- Protein Conformation MeSH
- Crystallography, X-Ray MeSH
- Ligands MeSH
- Evolution, Molecular * MeSH
- Models, Molecular MeSH
- Mutation MeSH
- Progesterone immunology MeSH
- Solubility MeSH
- Temperature MeSH
- Binding Sites, Antibody MeSH
- Hydrogen Bonding MeSH
- Publication type
- Journal Article MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
- Research Support, U.S. Gov't, P.H.S. MeSH
Accurate estimation of protein-ligand binding affinity is the cornerstone of computer-aided drug design. We present a universal physics-based scoring function, named SQM2.20, addressing key terms of binding free energy using semiempirical quantum-mechanical computational methods. SQM2.20 incorporates the latest methodological advances while remaining computationally efficient even for systems with thousands of atoms. To validate it rigorously, we have compiled and made available the PL-REX benchmark dataset consisting of high-resolution crystal structures and reliable experimental affinities for ten diverse protein targets. Comparative assessments demonstrate that SQM2.20 outperforms other scoring methods and reaches a level of accuracy similar to much more expensive DFT calculations. In the PL-REX dataset, it achieves excellent correlation with experimental data (average R2 = 0.69) and exhibits consistent performance across all targets. In contrast to DFT, SQM2.20 provides affinity predictions in minutes, making it suitable for practical applications in hit identification or lead optimization.
- MeSH
- Ligands MeSH
- Proteins * metabolism MeSH
- Drug Design * MeSH
- Thermodynamics MeSH
- Protein Binding MeSH
- Publication type
- Journal Article MeSH
The traditional way of rationally engineering enzymes to change their biocatalytic properties utilizes the modifications of their active sites. Another emerging approach is the engineering of structural features involved in the exchange of ligands between buried active sites and the surrounding solvent. However, surprisingly little is known about the effects of mutations that alter the access tunnels on the enzymes' catalytic properties, and how these tunnels should be redesigned to allow fast passage of cognate substrates and products. Thus, we have systematically studied the effects of single-point mutations in a tunnel-lining residue of a haloalkane dehalogenase on the binding kinetics and catalytic conversion of both linear and branched haloalkanes. The hotspot residue Y176 was identified using computer simulations and randomized through saturation mutagenesis, and the resulting variants were screened for shifts in binding rates. Strikingly, opposite effects of the substituted residues on the catalytic efficiency toward linear and branched substrates were observed, which was found to be due to substrate-specific requirements in the critical steps of the respective catalytic cycles. We conclude that not only the catalytic sites, but also the access pathways must be tailored specifically for each individual ligand, which is a new paradigm in protein engineering and de novo protein design. A rational approach is proposed here to address more effectively the task of designing ligand-specific tunnels using computational tools.
- MeSH
- Alkanes chemistry metabolism MeSH
- Biocatalysis MeSH
- Hydrocarbons, Halogenated chemistry metabolism MeSH
- Hydrolases chemistry genetics metabolism MeSH
- Catalytic Domain genetics MeSH
- Kinetics MeSH
- Ligands MeSH
- Molecular Structure MeSH
- Mutagenesis, Site-Directed methods MeSH
- Protein Domains MeSH
- Protein Engineering methods MeSH
- Molecular Dynamics Simulation MeSH
- Substrate Specificity MeSH
- Protein Binding MeSH
- Binding Sites genetics MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Carbonyl-reducing enzymes are important in both metabolism of endogenous substances and biotransformation of xenobiotics. Because sufficient amounts of native enzymes must be obtained to study their roles in metabolism, an efficient purification strategy is very important. Oracin (6-[2-(2-hydroxyethyl)aminoethyl]-5,11-dioxo-5,6-dihydro-11H-indeno[1,2-c] isoquinoline) is a prospective anticancer drug and one of the xenobiotic substrates for carbonyl-reducing enzymes. A new purification strategy based on molecular recognition of carbonyl-reducing enzymes with oracin as a ligand is reported here. The type of covalent bond, ligand molecules orientation, and their distance from the backbone of the solid matrix for good stearic accessibility were taken into account during the designing of the carrier. The carriers based on magnetically active microparticles were tested by recombinant enzymes AKR1C3 and CBR1. The SiMAG-COOH magnetic microparticles with N-alkylated oracin and BAPA as spacer arm provide required parameters: proper selectivity and specificity enabling to isolate the target enzyme in sufficient quantity, purity, and activity.
- MeSH
- Alcohol Oxidoreductases isolation & purification MeSH
- Biological Assay MeSH
- Chromatography, Affinity MeSH
- Electrophoresis, Polyacrylamide Gel MeSH
- Enzyme Assays methods MeSH
- Enzymes isolation & purification MeSH
- Ethanolamines chemistry MeSH
- Isoquinolines chemistry MeSH
- Ligands MeSH
- Magnetics * MeSH
- Microspheres MeSH
- Molecular Structure MeSH
- Antineoplastic Agents chemistry MeSH
- Schiff Bases chemistry MeSH
- Chromatography, High Pressure Liquid MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Galectins are proteins of the family of human lectins. By binding terminal galactose units of cell surface glycans, they moderate biological and pathological processes such as cell signaling, cell adhesion, apoptosis, fibrosis, carcinogenesis, and metabolic disorders. The binding of monovalent glycans to galectins is usually relatively weak. Therefore, the presentation of carbohydrate ligands on multivalent scaffolds can efficiently increase and/or discriminate the affinity of the glycoconjugate to different galectins. A library of glycoclusters and glycodendrimers with various structural presentations of the common functionalized N-acetyllactosamine ligand was prepared to evaluate how the mode of presentation affects the affinity and selectivity to the two most abundant galectins, galectin-1 (Gal-1) and galectin-3 (Gal-3). In addition, the effect of a one- to two-unit carbohydrate spacer on the affinity of the glycoconjugates was determined. A new design of the biolayer interferometry (BLI) method with specific AVI-tagged constructs was used to determine the affinity to galectins, and compared with the gold-standard method of isothermal titration calorimetry (ITC). This study reveals new routes to low nanomolar glycoconjugate inhibitors of galectins of interest for biomedical research.
- MeSH
- Galectins * metabolism MeSH
- Glycoconjugates * pharmacology chemistry MeSH
- Humans MeSH
- Ligands MeSH
- Polysaccharides metabolism MeSH
- Carbohydrates chemistry MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
The adverse side effects and acquired resistance associated with the clinical application of traditional platinum-based anticancer drugs have forced investigation of alternative transition metal-based compounds and their cytostatic properties. Over the last years, the anticancer potential of cobalt complexes has been extensively studied, and in-depth analyses of their mode of action have been conducted. In this work, we present antiproliferative activity against human cancer cells of the dinuclear Co(III) complexes bearing the quinizarin ligand and tris(2-aminoethyl)amine (tren, compound 1) or tris(2-pyridylmethyl)amine (tpa, compound 2) co-ligands. To contribute the understanding mechanisms of biological action of these compounds, their association with DNA in the cells, DNA binding in cell-free media, and DNA cleavage capability were investigated in detail. The results demonstrate that both complexes interact with DNA in tumor cells. However, their mechanism of antiproliferative action is different, and this difference is mirrored by distinct antiproliferative activity. The antiproliferative effect of 1 is connected with its ability to intercalate into DNA and subsequently to inhibit activities of DNA processing enzymes. In contrast, the total antiproliferative efficiency of 2, thanks to its redox properties, appears to be connected with its ability to form radicals and, consequently, with the ability of 2 to cleave DNA. Hence, the findings presented in this study may significantly contribute to understanding the antitumor potential of cobalt complexes. Dinuclear Co(III) complexes containing the bioactive quinizarin ligand exhibit antiproliferative activity based on distinct mechanism.
- MeSH
- Anthraquinones chemistry pharmacology MeSH
- DNA chemistry MeSH
- Cobalt chemistry pharmacology MeSH
- Coordination Complexes chemical synthesis chemistry pharmacology MeSH
- Humans MeSH
- Ligands MeSH
- Molecular Conformation MeSH
- Tumor Cells, Cultured MeSH
- Cell Proliferation drug effects MeSH
- Antineoplastic Agents chemical synthesis chemistry pharmacology MeSH
- Drug Screening Assays, Antitumor MeSH
- DNA Cleavage MeSH
- Binding Sites drug effects MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Anionic cyclopentadienyl (Cp) and its pentamethyl-substituted derivative (Cp*) serve as crucial ligands for creating stable π-coordinated materials, including catalysts. From a structural perspective, the π-extended analog of Cp, known as an N-fused porphyrin (NFP), is recognized as an intriguing 18π aromatic chromophore, offering near-infrared (NIR) optical properties that can be fine-tuned through metal complexation. When coordinated with rhodium at the central NFP core, it forms a sandwich binuclear rhodium(III) complex along with terminal and bridging chloride ligands, denoted as Rh-1, and its bromo derivative, Rh-1-Br. In contrast to the bis-NFP complex of iron(II) reported previously by our team, both Rh-1 and Rh-1-Br complexes exhibit strong NIR optical properties and narrow HOMO-LUMO energy gaps, attributed to minimal orbital interactions between the two co-facial NFP ligands. Leveraging these NIR absorption properties, we assessed the photothermal conversion properties of Rh-1 and ligand 1, revealing high conversion efficiency. This suggests their potential application as photothermal agents for use in photothermal therapy.
