1. SUMMARYMyeloperoxidase (MPO) which belongs to the peroxidase family, is found in mammalian neutrophils. This heme enzyme contributes to the production of (pseudo)halogenous acid such as HOCl which oxidizes proteins, cell membrane, DNA and RNA causing death for the pathogens. It has an antimicrobial effect due to HOCl secreting inside the phagosomes of the neutrophils, whereas it will be released outside neutrophils causing oxidative damages for the host tissues. Proteins, lipids, lipoproteins, DNA and RNA are potential targets of the MPO resulting in several chronic syndromes. Many researchers have discovered the harmful effects of MPO and its products demonstrating its role in many inflammatory chronic diseases such as: Cardiovascular diseases as in atherosclerosis. MPO contribution in atherosclerosis development has been demonstrated. Neurodegenerative diseases also was related to MPO: such as Alzheimer’s disease (AD), multiple sclerosis (MSc) and Parkinson’s disease The enzyme has been also pointed out in other diseases such as renal disease and cancer.For these reasons, MPO as a target of drug discovery has attracted the attention of many researchers. X-ray 3D structures were resolved for this enzyme, biological activity and mechanism of action were investigated in depth, and many medicinal chemists have investigated and screened for new MPO inhibitors. Indeed, this cumulative work including X-ray data, the role of MPO in different pathologies, MPO inhibitory mechanism of action, screening and various chemical entities that inhibit MPO, provided sufficient elements to start a new drug design and drug discovery process on MPO.The aim of the present study was to apply a rational drug design approach to the myeloperoxidase inhibition: from in silico to pharmacological activity. This includes:─ Conducting high throughput virtual screening in order to find new potential hits to inhibit MPO followed by mechanism of inhibition determination. ─ Selecting one hit and then implementing a whole pharmacomodulation process in order to increase the potency of the inhibition greater than the starting hit and to improve the selectivity.Firstly, a rational drug design process was launched to find new hits using high throughput virtual screening. The chosen database for the screening was ASINEX database published in ZINC.X-ray structure of human peroxidase complexed to cyanide and thiocyanate (PDB 1DNW) was selected to conduct High-Throughput Virtual Screening (HTVS). Three successive protocols with different levels of accuracy in the docking and scoring processes were used starting with HTVS, followed by Standard Precision (SP) and finally with Xtra Precision (XP). The quality of the docking process performed was validated by docking a set of 60 chosen molecules of varying chemical structure and known as MPO inhibitors. From the result of the HTVS conducted on 1,350,000 compounds, the 100 best compounds were selected. Among them, 81 molecules were available for purchase from ASINEX, those compounds were tested with a MPO inhibition assay. Thirty-two compounds (39 %) were active, but only 8 compounds were selected, featuring different chemical structures with IC50 values ranging between 0.46 ± 0.07 and 12 ± 3 μM. Among these molecules, two compounds were the best and considered as hits. One has purinedione structure which is similar with the structure of thioxanthine derivatives (F9, IC50=0.46±0.07μM). The second compound has a hexahydropyrimidine structure (A1, IC50 = 0.5 ± 0.1 μM) The most common interactions found among all 8 docked ligands are the ionic bond with Glu102 and a stacking (shifted or not) with pyrrole ring D of the prosthetic group. Hydrogen bonds with Glu102, Thr100, Gln91, Arg239, or the propionate groups of the heme are also found in several docked geometries of the complexes. Interestingly, interactions with Glu102 and pyrrole ring D of the heme were also seen with fluorotryptamine derivatives and also salicylhydroxamic acid (SHA).For measuring MPO-dependent LDL oxidation, the two best compounds were tested. Compounds A1 and F9 showed good inhibition on MPO-dependent LDL oxidation (62 ± 6, 4.5 ± 0.9, 11 ± 2% and 11 ± 2, 2.6 ± 0.8, 6 ± 4%, respectively).Consequently, in order to determine the mechanism of inhibition transient-state kinetics were further investigated of all the 8 selected compounds.Both new lead compounds (A1 and F9) act as electron donors of both Compound I and Compound II of MPO. The reaction with Compound I was significantly faster (k2 ≫ k3). As a consequence, the enzyme is trapped in the Compound II state. They reversibly inactivated the enzyme blocking the harmful halogenation activity of MPO by transferring it to the MPO peroxidase cycle. In the present study, 8 active and reversible MPO inhibitors were selected. They act as electron donors of the oxidoreductase and efficiently block the halogenation activity with reversible inactivation. Two of the selected compounds have a submicromolar activity and inhibit MPO-dependent LDL oxidation. The high-throughput virtual screening was proved to be a successful tool to find new leads of MPO inhibitors. Conducting HTVS on a large-scale database enabled selection of novel scaffolds of MPO inhibitors never explored before in less time and at less expenses.Finding 8 new different chemical scaffolds through the first step of this drug discovery process led us to choose a new hit, compound A1, which has a hexahydropyrimidine structure, compound F9 was not chosen despite being more active due to its similarity to compounds discovered by AstraZeneca. To conduct pharmacomodulation, a validation of the docking procedure was conducted by comparing the X-ray structures of MPO with 2-(3,5-bistrifluoromethylbenzylamino)-6-oxo-1H-pyrimidine-5- carbohydroxamic acid, HX1, and SHA in the X-ray structures of human MPO in complex with cyanide and thiocyanate (PDB code 1DNW) as well as in complex with HX1 (PDB code 4C1M). Compound A1 was docked into both target structures 1DNW and 4C1M. In both cases, A1 showed almost the same poses.Based on the binding modes of A1, different strategies were developed for the design of derivatives which were mainly focused on the substitution of the aromatic rings A and B, the 2 amino groups and the side chain bridges.Pharmacomodulation was carried out on the hit A1 with different strategies:─ Investigating the role of hydroxyl groups on both aromatic rings─ Shifting the position of the amino groups in the hexahydropyrimidine ring to obtain piperazine derivatives and introduction of fluorine ─ Eliminating of one ring and of an amino group in the hexahydropyrimidine ring leading to piperidine derivatives ─ Opening the hexahydropyrimidine ring while keeping amine function and changing the length of the bridge between this amino group and aromatic ring as well as the impact of substitutions on aromatic rings.─ Hybridization of fluorotryptamine derivatives (effective MPO inhibitors) with hit A1.Based on of the docking experiments, 37 designed compounds were synthesized. The assessment of inhibition of the chlorination activity of MPO was undertaken over the 37 compounds. The hit A1 IC50 = 500 nM. The best compounds inhibiting MPO exhibited the following characteristics:─ One amino group on the bridge between aromatic rings was sufficient for the establishment of binding to Glu102 ─ The presence of three methylene groups between the secondary amine and an aromatic ring improved the inhibition of chlorination and thus decreased the IC50 values. These results showed that the position of the hydroxyl group is important. The distance between the hydrogen bond acceptor (HBA) group of one aromatic ring and the amino group is very important. The docking experiments of bisarylpropylamine derivatives showed ionic and hydrogen bonding interactions between Glu102 and hydroxyl group on aromatic ring linked to the longer side chain.─ Hybridized compounds which carry a fluorotryptamine instead of the phenol ring obtained by hybridization of hit A1 and the potent MPO inhibitors fluorotryptamine derivatives. Actually, compound 38 (which had one aromatic ring and a propyl bridge attached to indole ring) had an IC50 = 54 nM which was 10 times more powerful than the starting hit.The 3 best compounds were tested to examine the transient kinetics. They act as electron donors of the oxidoreductase and efficiently shift MPO from the chlorination cycle to the peroxidase cycle. Due to the similarity of the best compound 38 to serotonin it was tested with the two other best compounds on serotonin transporter (SERT) to examine the selectivity between MPO and SERT.Compound 38 had higher selectivity over MPO but the best selective compound was 28 that contains two aromatic rings carrying one hydroxyl and one fluorine.Electron density maps were conducted to predict the site of oxidation. Results suggested it occurs preferentially at the benzene ring or the indole ring in the best compounds.Determination of redox potentials for the synthesized compounds were tested. Best compounds act as electron donors allowing a one-electron reduction of Compound I.In conclusion, the present study succeeded through rational drug design including structure-based drug design and HTVS to identify new chemical entities for MPO inhibition. Eight compounds were more active than the starting hit A1 with submicromolar inhibition potency. Hybridization and structure based design also gave improvement of selectivity of inhibitors against MPO such as compound 38. Bis-arylalkylamine derivatives are a new group of MPO inhibitors with higher selectivity which could be a new hit for future development. / Doctorat en Sciences biomédicales et pharmaceutiques (Pharmacie) / info:eu-repo/semantics/nonPublished

Serum C-reactive protein (CRP) is used as a marker of inflammation in several diseases including autoimmune disease and cardiovascular disease. CRP, a member of the pentraxin family, is comprised of five identical subunits. CRP has diverse ligand-binding properties which depend upon different structural states of CRP. However, little is known about the molecular dynamics and interaction properties of CRP. In this study, we used SAPS, SCRATCH protein predictor, PDBsum, ConSurf, ProtScale, Drawhca, ASAView, SCide and SRide server and performed comprehensive analyses of molecular dynamics, protein-protein and residue-residue interactions of CRP. We used 1GNH.pdb file for the crystal structure of human CRP which generated two pentamers (ABCDE and FGHIJ). The number of residues involved in residue-residue interactions between A-B, B-C, C-D, D-E, F-G, G-H, H-I, I-J, A-E and F-J subunits were 12, 11, 10, 11, 12, 11, 10, 11, 10 and 10, respectively. Fifteen antiparallel β sheets were involved in β-sheet topology, and five β hairpins were involved in forming the secondary structure. Analysis of hydrophobic segment distribution revealed deviations in surface hydrophobicity at different cavities present in CRP. Approximately 33 % of all residues were involved in the stabilization centers. We show that the bioinformatics tools can provide a rapid method to predict molecular dynamics and interaction properties of CRP. Our prediction of molecular dynamics and interaction properties of CRP combined with the modeling data based on the known 3D structure of CRP is helpful in designing stable forms of CRP mutants for structure-function studies of CRP and may facilitate in silico drug design for therapeutic targeting of CRP.

Serum C-reactive protein (CRP) is used as a marker of inflammation in several diseases including autoimmune disease and cardiovascular disease. CRP, a member of the pentraxin family, is comprised of five identical subunits. CRP has diverse ligand-binding properties which depend upon different structural states of CRP. However, little is known about the molecular dynamics and interaction properties of CRP. In this study, we used SAPS, SCRATCH protein predictor, PDBsum, ConSurf, ProtScale, Drawhca, ASAView, SCide and SRide server and performed comprehensive analyses of molecular dynamics, protein-protein and residue-residue interactions of CRP. We used 1GNH.pdb file for the crystal structure of human CRP which generated two pentamers (ABCDE and FGHIJ). The number of residues involved in residue-residue interactions between A-B, B-C, C-D, D-E, F-G, G-H, H-I, I-J, A-E and F-J subunits were 12, 11, 10, 11, 12, 11, 10, 11, 10 and 10, respectively. Fifteen antiparallel β sheets were involved in β-sheet topology, and five β hairpins were involved in forming the secondary structure. Analysis of hydrophobic segment distribution revealed deviations in surface hydrophobicity at different cavities present in CRP. Approximately 33 % of all residues were involved in the stabilization centers. We show that the bioinformatics tools can provide a rapid method to predict molecular dynamics and interaction properties of CRP. Our prediction of molecular dynamics and interaction properties of CRP combined with the modeling data based on the known 3D structure of CRP is helpful in designing stable forms of CRP mutants for structure-function studies of CRP and may facilitate in silico drug design for therapeutic targeting of CRP.

Protein-protein interactions build large networks which are essential in understanding complex diseases. Due to limitations of experimental methodology there are problems with large amounts of false negative and positive interactions; and a large gap in the amount of known interactions and structurally determined interactions. By using computational methods these problems can be alleviated. In this thesis the quality of a newly developed pipeline (InterPred) were investigated for its ability to generate coarse interaction models and score them. This ability was investigated by performing docking experiments in Rosetta on models generated in InterPred. The results suggest that InterPred is highly successful in generating good starting points for docking proteins in silico and to distinguish the quality of models.

No / Quality assessment (QA) requires high levels of domain-specific experience and knowledge. QA tasks for toxicological data are usually performed by human experts manually, although a number of quality evaluation schemes have been proposed in the literature. For instance, the most widely utilised Klimisch scheme1 defines four data quality categories in order to tag data instances with respect to their qualities; ToxRTool2 is an extension of the Klimisch approach aiming to increase the transparency and harmonisation of the approach. Note that the processes of QA in many other areas have been automatised by employing expert systems. Briefly, an expert system is a computer program that uses a knowledge base built upon human expertise, and an inference engine that mimics the reasoning processes of human experts to infer new statements from incoming data. In particular, expert systems have been extended to deal with the uncertainty of information by representing uncertain information (such as linguistic terms) as fuzzy sets under the framework of fuzzy set theory and performing inferences upon fuzzy sets according to fuzzy arithmetic. This paper presents an experimental fuzzy expert system for toxicological data QA which is developed on the basis of the Klimisch approach and the ToxRTool in an effort to illustrate the power of expert systems to toxicologists, and to examine if fuzzy expert systems are a viable solution for QA of toxicological data. Such direction still faces great difficulties due to the well-known common challenge of toxicological data QA that "five toxicologists may have six opinions". In the meantime, this challenge may offer an opportunity for expert systems because the construction and refinement of the knowledge base could be a converging process of different opinions which is of significant importance for regulatory policy making under the regulation of REACH, though a consensus may never be reached. Also, in order to facilitate the implementation of Weight of Evidence approaches and in silico modelling proposed by REACH, there is a higher appeal of numerical quality values than nominal (categorical) ones, where the proposed fuzzy expert system could help. Most importantly, the deriving processes of quality values generated in this way are fully transparent, and thus comprehensible, for final users, which is another vital point for policy making specified in REACH. Case studies have been conducted and this report not only shows the promise of the approach, but also demonstrates the difficulties of the approach and thus indicates areas for future development. / U 7th Framework Programme Integrated Project “Integrated In Silico Models for Prediction of Human Repeated Dose Toxicity of Cosmetics to Optimise Safety” (COSMOS). Grant Number: 266835. Cosmetics Europe.

Subsurface microbes are extremophiles adapted to thrive in deep, resource-limited environments, performing crucial roles in a myriad of biogeochemical processes. The extremozymes they produce might play a pivotal role in catalyzing these processes. Identifying and characterizing those enzymes could contribute to the advancements in industrially important biocatalytic reactions. Among various enzymes, sorbitol dehydrogenases are enzymes that catalyze the reversible conversion of sorbitol into fructose in the presence of NAD+. In this study, we focus on the exploration of a sorbitol dehydrogenase (SDHSIUC1) derived from the novel strictly anaerobic, thermophilic, subsurface bacterium, Caldiatribacterium inferamans SIUC1, which is one of the first cultured members from the candidate phylum Atribacteria OP9. As SDHSIUC1 originated from a subsurface microbe, we hypothesized that the enzyme has industrially beneficial characteristics such as higher thermostability and can be used for bioindustry applications such as synthesis of rare sugars and chiral alcohols. We successfully cloned, expressed, and purified the functional SDHSIUC1 enzyme aerobically using E. coli BL21(DE3) and did biochemical assays to characterize its properties. Additionally, in combination with the findings of biochemical characterization, we applied in silico approaches such as molecular modeling and molecular docking to describe the functional mechanism of the enzyme. Initial phylogenetic tree analysis using a pool of 24 amino acid sequences showed that the closest relative for SDHSIUC1 is a Candidatus Caldiatribacterium californiense, which is an uncultured member of the Atribacteria phylum. Size exclusion chromatography and Native-PAGE suggested that SDHSIUC1 is a hexamer with a size of 225 kDa. Kinetic characterization of the SDHSIUC1 showed that the enzyme has a higher affinity for sorbitol and fructose in the presence of NAD+ and NADH, respectively. Furthermore, SDHSIUC1 enzyme is promiscuous as it could utilize other polyols (i.e., glycerol, xylitol, inositol), diols (i.e., butanediol), aldehydes (i.e., glycolaldehyde), and ketoses (i.e., sorbose) in the presence of NAD+/NADH cofactors. We observed a significant increase in enzyme activity in the presence of Zn2+, where other metal ions such as Mn2+ and Mg2+ also resulted in rate improvements. The enzyme is an alkaline dehydrogenase that prefers a higher pH above 8. The effect of temperature on SDHSIUC1 activity showed that it’s a thermophilic enzyme with activity at 85 ℃. The thermal denaturation points of the enzyme at 85 ℃ was increased when the enzyme was preincubated at 85 ℃ in the presence of Zn2+. Notably, the enzyme preincubated 25 min at 85 ℃ in the presence of Zn2+ prefers fructose conversion and ceased the sorbitol conversion. We identified the presence of a structural Zn2+ binding site in SDHSIUC1 in addition to a catalytic Zn2+ binding site. We speculated that the structural Zn2+ involves thermal stability of the enzyme. Hence, we mutated the cysteine with serine of potential structural Zn2+ binding site (Cys96, Cys99, Cys102, and Cys110). Indeed, the Inductively coupled plasma mass spectrometry (ICP-MS) analysis revealed the mutated enzyme contains a lower amount of Zn2+ relative to the native enzyme. The data revealed that the mutated enzyme has low melting temperature (78 ℃) relative to the native enzyme (92 ℃), suggesting that structural Zn2+ is key to enhance the thermal stability of the SDHSIUC1. Surprisingly, we observed that the mutant enzyme completely lost its activity. The data suggests the role of structural Zn2+ binding site on both the structural and functional stability of SDHSIUC1. In consistence with the in-vitro data, the preliminary computational modeling data suggest that the losing structural Zn2+ unstable the enzyme and we are conducting in depth in-silico study to unveil the mechanism(s). We envisioned that the mechanisms behind the thermal stability of SDHSIUC1 could be used as basic model to enhance thermostable protein for the industrial application (e.g., design thermostable plastic hydrolyzing enzymes). To further demonstrate the potential applications of the SDHSIUC1, we genome-integrated it into the industrially important microorganism Pseudomonas putida KT2440. The resulting strain exhibited significantly increased growth in the presence of sorbitol compared to the wild-type P. putida KT2440, highlighting the potential of this enzyme for industrial applications such as enabling sorbitol catabolism or establishing xylose reductase pathway in P. putida KT2440 (i.e., leverage xylitol dehydrogenase activity of SDHSIUC1). In summary, this study has uncovered a novel thermostable sorbitol dehydrogenase from a subsurface microbe, which could have potential applications in the bioindustry where thermostable sorbitol dehydrogenases are required for the application in food and beverage industry, pharmaceutical industry, biofuel production etc. as it would be advantageous for the industrial processes.

No description available.

Lanthionine synthetase C-like protein 2 (LANCL2) is a member of the LANCL protein family, which is broadly expressed throughout the body. LANCL2 is the molecular target of abscisic acid (ABA), a compound with insulin-sensitizing and immune modulatory actions. LANCL2 is required for membrane binding and signaling of ABA in immune cells. Direct binding of ABA to LANCL2 was predicted in silico using molecular modeling approaches and validated experimentally using ligand-binding assays and kinetic surface plasmon resonance studies. The therapeutic potential of the LANCL2 pathway ranges from increasing cellular sensitivity to anticancer drugs, insulin-sensitizing effects and modulating immune and inflammatory responses in the context of immune-mediated and infectious diseases. A case for LANCL2-based drug discovery and development is also illustrated by the anti-inflammatory activity of novel LANCL2 ligands such as NSC61610 against inflammatory bowel disease in mice. This dissertation discusses the value of LANCL2 as a novel therapeutic target for the discovery and development of new classes of orally active drugs against chronic metabolic, immune-mediated and infectious diseases and as a validated target that can be used in precision medicine. Specifically, in Chapter 2 of the dissertation, we performed homology modeling to construct a three-dimensional structure of LANCL2 using the crystal structure of LANCL1 as a template. Our molecular docking studies predicted that ABA and other PPAR - agonists share a binding site on the surface of LANCL2. In Chapter 3 of the dissertation, structure-based virtual screening was performed. Several potential ligands were identified using molecular docking. In order to validate the anti-inflammatory efficacy of the top ranked compound (NSC61610) in the NCI Diversity Set II, a series of in vitro and pre-clinical efficacy studies were performed using a mouse model of dextran sodium sulfate (DSS)-induced colitis. In Chapter 4 of the dissertation, we developed a novel integrated approach for creating a synthetic patient population and testing the efficacy of the novel pre-clinical stage LANCL2 therapeutic for Crohn's disease in large clinical cohorts in silico. Efficacy of treatments on Crohn's disease was evaluated by analyzing predicted changes of Crohn's disease activity index (CDAI) scores and correlations with immunological variables were evaluated. The results from our placebo-controlled, randomized, Phase III in silico clinical trial at 6 weeks following the treatment shows a positive correlation between the initial disease activity score and the drop in CDAI score. This observation highlights the need for precision medicine strategies for IBD. / Ph. D.

Optical Point-of-Care (POC) devices provide a low-cost platform for real-time, non-invasive diagnosis of disease and quantitative estimation of physiological biomarkers, allowing use in a wide variety of institutional settings ranging from acute surgical care to long-term clinical monitoring. POC optical value has resulted in their widespread adoption with great interest in at-home monitoring and explosive growth within wearable consumer electronics. However, recent studies have highlighted the fact that well-established devices such as pulse oximeters can exhibit subtle but dangerous inaccuracies in measurements from some darker skin pigmentation patients whose basis is not completely understood. Emerging optical technologies, such as near-infrared spectroscopy (NIRS) monitoring of bone quality are promising, yet similarly suffer from an incomplete understanding of the relationship between probe design and performance.The focus of this dissertation is to develop next-generation approaches to improve the performance of optical diagnostic devices informed by computational simulations of light-tissue interactions using Monte Carlo (MC) modeling. Although MC simulations have been previously used to design and simulate devices such as Pulse Oximeters or Transcutaneous Bilirubinometers (TcB), the simulations were incapable of capturing population-level heterogeneity and thus evaluating underlying factors contributing to measurement bias. Here, an in-silico MC platform was developed to investigate how population-level heterogeneity impacts Pulse Oximeters and TcB devices. The results demonstrate that fundamental biases in optical measurements exist and are exacerbated by inequitable regulatory guidelines. These findings were used to further demonstrate the impact of changes in regulatory guidelines that can affect measurement accuracy and clinical decision-making. Additionally, simulation results were used to inform the development of spectroscopic oximetry and demonstrate the techniques clinical feasibility and potential to improve accuracy in a human-subjects pilot study. In the case of the NIRS bone quality assessment, a lack of fundamental knowledge of tissue optical properties to allow simulations to inform relative contributions from different tissue features to the overall signal or explore optimization of device design. Studies were performed to collect previously unreported optical properties from musculoskeletal tissues, and this data was used to perform MC simulations which informed bone contribution to NIRS signals and in turn resulted in the design and preliminary characterization of next-generation fiber optic probes for real-time non-ionizing assessment of bone quality. Collectively, this dissertation demonstrates the impact of advances in MC simulations of light-tissue interaction across pressing clinically focused engineering challenges. / Bioengineering

Yes / New multicomponent solid forms of sildenafil have been discovered by means of a combined virtual/experimental cocrystal screening. Coformer selection of candidates was conducted based on an in silico screening method from a database of more than 2000 organic compounds, and the intensive experimental screen produced 23 new solid forms. Since the 12 coformers chosen have a combination of phenol and carboxylic acid groups, a variety of cocrystals, salts, and hybrid salt-cocrystals were discovered and characterized.