Publications by authors named "Krzysztof Okrasa"

Current therapies for Alzheimer's disease seek to correct for defective cholinergic transmission by preventing the breakdown of acetylcholine through inhibition of acetylcholinesterase, these however have limited clinical efficacy. An alternative approach is to directly activate cholinergic receptors responsible for learning and memory. The M1-muscarinic acetylcholine (M1) receptor is the target of choice but has been hampered by adverse effects.

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A series of novel allosteric antagonists of the GLP-1 receptor (GLP-1R), exemplified by HTL26119, are described. SBDD approaches were employed to identify HTL26119, exploiting structural understanding of the allosteric binding site of the closely related Glucagon receptor (GCGR) (Jazayeri et al., 2016) and the homology relationships between GCGR and GLP-1R.

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Two interesting new X-ray structures of negative allosteric modulator (NAM) ligands for the mGlu receptor, M-MPEP (3) and fenobam (4), are reported. The new structures show how the binding of the ligands induces different receptor water channel conformations to previously published structures. The structure of fenobam, where a urea replaces the acetylenic linker in M-MPEP and mavoglurant, reveals a binding mode where the ligand is rotated by 180° compared to a previously proposed docking model.

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Fragment screening of a thermostabilized mGlu5 receptor using a high-concentration radioligand binding assay enabled the identification of moderate affinity, high ligand efficiency (LE) pyrimidine hit 5. Subsequent optimization using structure-based drug discovery methods led to the selection of 25, HTL14242, as an advanced lead compound for further development. Structures of the stabilized mGlu5 receptor complexed with 25 and another molecule in the series, 14, were determined at resolutions of 2.

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Metabotropic glutamate receptors are class C G-protein-coupled receptors which respond to the neurotransmitter glutamate. Structural studies have been restricted to the amino-terminal extracellular domain, providing little understanding of the membrane-spanning signal transduction domain. Metabotropic glutamate receptor 5 is of considerable interest as a drug target in the treatment of fragile X syndrome, autism, depression, anxiety, addiction and movement disorders.

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It has been shown that the genomes of episomally maintained DNA viruses are tethered to host cell chromosomes during cell division, facilitating maintenance in dividing cells. The papillomavirus E2 protein serves this mechanism of viral genome persistence by simultaneously associating with chromatin and the viral genome during mitosis. Several host cell proteins are reported to be necessary for the association of E2 with chromatin including the cohesion establishment factor ChlR1.

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The immobilisation of proteins on to nanoparticles has a number of applications ranging from biocatalysis through to cellular delivery of biopharmaceuticals. Here we describe a phosphopantetheinyl transferase (Sfp)-catalysed method for immobilising proteins bearing a small 12-mer "ybbR" tag on to nanoparticles functionalised with coenzyme A. The Sfp-catalysed immobilisation of proteins on to nanoparticles is a highly efficient, single step reaction that proceeds under mild conditions and results in a homogeneous population of proteins that are covalently and site-specifically attached to the surface of the nanoparticles.

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One useful synthetic reaction missing from nature's toolbox is the direct hydrogenation of substrates using hydrogen. Instead nature uses cofactors like NADH to reduce organic substrates, which adds complexity and cost to these reductions. To create an enzyme that can directly reduce organic substrates with hydrogen, researchers have combined metal hydrogenation catalysts with proteins.

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Article Synopsis
  • Researchers used Candida antarctica lipase B to catalyze the ring-opening polymerization of five lactones in ionic liquids, producing poly(hydroxyalkanoates) with moderate molecular weights (up to 13,000).
  • The study found that using the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethane)-sulfonimide and a low enzyme-to-lactone ratio led to significant degrees of polymerization for various lactones.
  • Water-immiscible ionic liquids were more effective than water-miscible ones, and reducing the water content in the enzyme increased polymerization efficiency by up to 50%.
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Carbonic anhydrase is a zinc metalloenzyme that catalyzes the hydration of carbon dioxide to bicarbonate. Replacing the active-site zinc with manganese yielded manganese-substituted carbonic anhydrase (CA[Mn]), which shows peroxidase activity with a bicarbonate-dependent mechanism. In the presence of bicarbonate and hydrogen peroxide, (CA[Mn]) catalyzed the efficient oxidation of o-dianisidine with kcat/KM=1.

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Degradation of 2,6-dichlorophenol (2,6-DCP) was accomplished by oxidation catalyzed by Coprinus cinereus peroxidase. Immobilization of the enzyme in a polyacrylamide matrix enhanced DCP oxidation. Hydrogen peroxide, peroxidase's natural substrate, was produced enzymatically in situ to avoid peroxidase inactivation by its too high concentration.

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