Darren Wragg

Bio: Darren Wragg is an academic researcher from Technische Universität München. The author has contributed to research in topics: Metadynamics & Aquaporin. The author has an hindex of 5, co-authored 10 publications receiving 128 citations. Previous affiliations of Darren Wragg include Cardiff University.

On the Mechanism of Gold/NHC Compounds Binding to DNA G-Quadruplexes: Combined Metadynamics and Biophysical Methods.

Abstract: The binding modes and free-energy landscape of two AuI /N-heterocyclic carbene complexes interacting with G-quadruplexes, namely a human telomeric (hTelo) and a promoter sequence (C-KIT1), are studied here for the first time by metadynamics. The theoretical results are validated by FRET DNA melting assays and provide an accurate estimate of the absolute gold complex/DNA binding free energy. This advanced in silico approach is valuable to achieve rational drug design of selective G4 binders.

Molecular Basis of Aquaporin-7 Permeability Regulation by pH.

Abstract: The aquaglyceroporin AQP7, a family member of aquaporin membrane channels, facilitates the permeation of water and glycerol through cell membranes and is crucial for body lipid and energy homeostasis. Regulation of glycerol permeability via AQP7 is considered a promising therapeutic strategy towards fat-related metabolic complications. Here, we used a yeast aqy-null strain for heterologous expression and functional analysis of human AQP7 and investigated its regulation by pH. Using a combination of in vitro and in silico approaches, we found that AQP7 changes from fully permeable to virtually closed at acidic pH, and that Tyr135 and His165 facing the extracellular environment are crucial residues for channel permeability. Moreover, instead of reducing the pore size, the protonation of key residues changes AQP7’s protein surface electrostatic charges, which, in turn, may decrease glycerol’s binding affinity to the pore, resulting in decreased permeability. In addition, since some pH-sensitive residues are located at the monomer-monomer interface, decreased permeability may result from cooperativity between AQP7’s monomers. Considering the importance of glycerol permeation via AQP7 in multiple pathophysiological conditions, this mechanism of hAQP7 pH-regulation may help the design of selective modulators targeting aquaglyceroporin-related disorders.

Templated Chromophore Assembly on Peptide Scaffolds: A Structural Evolution

Abstract: The use of a template bearing pre‐programmed receptor sites selectively accommodating chromophores at given positions is an attractive approach for engineering artificial light‐harvesting systems. Indulging this line of though, this work tackles the creation of tailored antenna architectures with yellow, red and blue chromophores exploiting three dynamic covalent reactions simultaneously, namely disulfide exchange, acyl hydrazone and boronic ester formations. The effect of various structural modifications, such as the chromophores as well as their spatial organization (distance, orientation, order), on the energy transfer within the antennas was studied by means of steady‐state UV‐Vis absorption and fluorescence spectroscopies. This systematic study allowed a significant improvement of the energy transfer efficiencies across the chromophores to a noticeable 22 and 15%, for the yellow and red donors to the blue acceptor, respectively. Metadynamics simulations suggested that the conformational properties of the antennas are driven by intramolecular chromophoric stacking interactions that, forcing the a‐helix to fold on itself, annul any effects deriving from the programming of the spatial arrangement of the receptor sides in the peptide backbone

Principles Of Fluorescence Spectroscopy

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Recent advances in gold-NHC complexes with biological properties

Abstract: This tutorial review covers the recent advances made in the study of gold complexes containing N-heterocyclic carbene ligands with biological properties. The great stability, ease of modulation of the electronic properties and excellent σ-donating capacity displayed by NHCs allow gold-NHC derivatives to reach high stability in biological media and relatively good internalization into cells and for that they have emerged as excellent potential chemotherapeutics. The new gold-NHC derivatives show superior anticancer activity compared to other standards such as Cisplatin or Auranofin. In addition, the application of gold-NHC complexes in the treatment of other human diseases as antibacterial, antioxidant and antiparasitic agents is reviewed for the first time.

Prognostic value and immune infiltration of novel signatures in clear cell renal cell carcinoma microenvironment.

Abstract: Growing evidence has highlighted the immune response as an important feature of carcinogenesis and therapeutic efficacy in clear cell renal cell carcinoma (ccRCC). This study categorized ccRCC cases into high and low score groups based on their immune/stromal scores generated by the ESTIMATE algorithm, and identified an association between these scores and prognosis. Differentially expressed tumor environment (TME)-related genes extracted from common upregulated components in immune and stromal scores were described using functional annotations and protein-protein interaction (PPI) networks. Most PPIs were selected for further prognostic investigation. Many additional previously neglected signatures, including AGPAT9, AQP7, HMGCS2, KLF15, MLXIPL, PPARGC1A, exhibited significant prognostic potential. In addition, multivariate Cox analysis indicated that MIXIPL and PPARGC1A were the most significant prognostic signatures, and were closely related to immune infiltration in TCGA cohort. External prognostic validation of MIXIPL and PPARGC1A was undertaken in 380 ccRCC cases from a real-world cohort. These findings indicate the relevance of monitoring and manipulation of the microenvironment for ccRCC prognosis and precision immunotherapy.

Gold(III) Complexes for Antitumor Applications: An Overview.

Abstract: Gold(III) complexes have emerged as a versatile and effective class of metal-based anticancer agents. The development of various types of ligands capable of stabilizing the AuIII cation and preventing its reduction under physiological conditions, such as chelating nitrogen-donors, dithiocarbamates and C^N cyclometalled ligands, has opened the way for the exploration of their potential intracellular targets and action mechanisms. At the same time, the bioconjugation of AuIII complexes has emerged as a promising strategy for improving the selectivity of this class of compounds for cancer cells over healthy tissues, and recent developments have shown that combining gold complexes with molecular structures that are specifically recognized by the cell can exploit the cell's own transport mechanisms to improve selective metal uptake.

Transition metal compounds as cancer radiosensitizers

Abstract: The concomitant administration of ionising radiation (IR) in the form of external beam radiotherapy or targeted radionuclide therapy (TRT) alongside radiosensitizing small molecules is a highly successful strategy for the treatment of cancer. The major clinical impact of the radiosensitizing platinum(II) drug cisplatin has encouraged the design of many transition metal coordination or organometallic complexes and their assessment as anticancer candidates. The growing recognition that metallodrugs halt cancer cell proliferation through mechanisms other than DNA damage and the recent expansion of the range of their potential biological targets has further stimulated the field. A central aim is to generate new therapeutic candidates with improved anticancer activity, distinct mechanisms of action(s) and reduced cross-resistance compared to existing drugs. The question arises of how lead candidates should be combined with other treatment modalities, particularly radiotherapy. In this review, work is highlighted that specifically examines transition metal complexes in combination with IR with an emphasis on complexes that function as radiosensitizers. The chemical design principles and cellular mechanisms of action to achieve synergistic or additive effects in cancer cell killing are outlined. Finally, we discuss emerging applications in this area of research, such as the combination of metallo-compound radiosensitizers with radionuclides and within drug delivery approaches.