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1.
Mechanistic insights into biological activities of polyphenolic compounds from rosemary obtained by inverse molecular docking
Samo Lešnik, Urban Bren, 2022, original scientific article

Abstract: Rosemary (Rosmarinus officinalis L.) represents a medicinal plant known for its various health-promoting properties. Its extracts and essential oils exhibit antioxidative, anti-inflammatory, anticarcinogenic, and antimicrobial activities. The main compounds responsible for these effects are the diterpenes carnosic acid, carnosol, and rosmanol, as well as the phenolic acid ester rosmarinic acid. However, surprisingly little is known about the molecular mechanisms responsible for the pharmacological activities of rosemary and its compounds. To discern these mechanisms, we performed a large-scale inverse molecular docking study to identify their potential protein targets. Listed compounds were separately docked into predicted binding sites of all non-redundant holo proteins from the Protein Data Bank and those with the top scores were further examined. We focused on proteins directly related to human health, including human and mammalian proteins as well as proteins from pathogenic bacteria, viruses, and parasites. The observed interactions of rosemary compounds indeed confirm the beforementioned activities, whereas we also identified their potential for anticoagulant and antiparasitic actions. The obtained results were carefully checked against the existing experimental findings from the scientific literature as well as further validated using both redocking procedures and retrospective metrics.
Keywords: rosemary, inverse molecular docking, carnosol, carnosic acid, rosmanol, rosmarinic acid
Published in DKUM: 10.04.2025; Views: 0; Downloads: 2
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Mehanizem stabilizacije humanega transportnega proteina transtiretina z rožmarinsko kislino
Meta Kočevar, 2020

Abstract: Dedna transtiretinska amiloidoza je avtosomno dominantna bolezen. Nastane kot posledica mutacije v proteinu transtiretinu. Mutacije povzročajo strukturne spremembe proteina, ki jim sledi disociacija v monomere in kasneje agregacija monomerov ter tvorba amiloidnih vlakenc. Vlakenca se nalagajo v tkivih kot so živčevje, srce in ledvice. Nestabilno strukturo proteina, ki jo povzročajo mutacije, je možno stabilizirati z vezavo majhnih molekul na protein. Ena izmed takšnih molekul je rožmarinska kislina. V magistrskem delu smo z uporabo računalniških simulacij molekulske dinamike ugotavljali, kako mutacija V30M vpliva na stabilnost strukture proteina transtiretina. Na protein smo vezali tudi rožmarinsko kislino in opazovali, ali se z vezavo stabilnost proteina spremeni. Pri tem smo uporabili dva različna načina parametrizacije polja sil za rožmarinsko kislino. Za pripravo 6 simulacij molekulske dinamike smo uporabili program CHARMM-GUI, za samo izvedbo simulacij pa program NAMD. Rezultate smo vizualno pregledali in analizirali s programoma Chimera in Cytoscape. Analiza trajektorij molekulskih dinamik je obsegala izračun srednjega kvadrata odstopanja, analizo vodikovih vezi in analizo vseh nekovalentnih kontaktov. Rezultati, ki smo jih pri tem dobili, kažejo, da mutacija V30M povzroči manj stabilno strukturo transtiretina. Avtomatsko parametrizirana rožmarinska kislina na stabilnost kompleksa protein-ligand za nemutirani protein ni imela velikega vpliva, medtem ko je ročno parametrizirana rožmarinska kislina zmanjšala število kontaktov med nemutiranim proteinom in ligandom. V primeru vezave ročno parametrizirane rožmarinske kisline pa smo zaznali veliko število kontaktov med proteinom in ligandom. Ob vezavi rožmarinske kisline na nemutirani protein smo zaznali manjšo stabilnost proteina. Vezava rožmarinske kisline na mutirani protein pa izboljša stabilnost proteina.
Keywords: transtiretin, transtiretinska amiloidoza, rožmarinska kislina, simulacije molekulske dinamike, polje sil, stabilnost proteina
Published in DKUM: 10.10.2024; Views: 0; Downloads: 36
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The effect of the Ala16Val mutation on the secondary structure of the manganese superoxide dismutase mitochondrial targeting sequence
Matic Broz, Veronika Furlan, Samo Lešnik, Marko Jukič, Urban Bren, 2022, original scientific article

Abstract: Manganese Superoxide Dismutase (MnSOD) represents a mitochondrial protein that scavenges reactive oxygen species (ROS) responsible for oxidative stress. A known single nucleotide polymorphism (SNP) rs4880 on the SOD2 gene, causing a mutation from alanine to valine (Ala16Val) in the primary structure of immature MnSOD, has been associated with several types of cancer and other autoimmune diseases. However, no conclusive correlation has been established yet. This study aims to determine the effect of the alanine to valine mutation on the secondary structure of the MnSOD mitochondrial targeting sequence (MTS). A model for each variant of the MTS was prepared and extensively simulated with molecular dynamics simulations using the CHARMM36m force field. The results indicate that the alanine variant of the MTS preserves a uniform α-helical secondary structure favorable for the protein transport into mitochondria, whereas the valine variant quickly breaks down its α-helix. Thus, the alanine MTS represents the more active MnSOD variant, the benefits of which have yet to be determined experimentally.
Keywords: manganese superoxide dismutase, polymorphism rs4880, mutation Ala16Val, molecular dynamics simulations, oxidative stress
Published in DKUM: 21.08.2023; Views: 370; Downloads: 18
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6.
Scaffold hopping and bioisosteric replacements based on binding site alignments
Samo Lešnik, Janez Konc, Dušanka Janežič, 2016, original scientific article

Abstract: Bioisosteric replacements and scaffold hopping play an important role in modern drug discovery and design, as they enable the change of either a core scaffold or substitutes in a drug structure, thereby facilitating optimization of pharmacokinetic properties and patenting, while the drug retains its activity. A new knowledge-based method was developed to obtain bioisosteric or scaffold replacements based on the extensive data existing in the Protein Data Bank. The method uses all-against-all ProBiS-based protein superimposition to identify ligand fragments that overlap in similar binding sites and could therefore be considered as bioisosteric replacements. The method was demonstrated on a specific example of drug candidate – a nanomolar butyrylcholinesterase inhibitor, on which bioisosteric replacements of the three ring fragments were performed. The new molecule containing bioisosteric replacements was evaluated virtually using AutoDock Vina; a similar score for the original and the compound with replacements was obtained, suggesting that the newly designed bioisostere compound might retain the potency of the original inhibitor.
Keywords: bioisosteres, scaffold hopping, protein alignment, ProBiS, drug design, analysis methods, matter structure, modelling
Published in DKUM: 05.07.2017; Views: 1237; Downloads: 431
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7.
Ligand-based virtual screening interface between PyMOL and LiSiCA
Athira Dilip, Samo Lešnik, Tanja Štular, Dušanka Janežič, Janez Konc, 2016, original scientific article

Abstract: Ligand-based virtual screening of large small-molecule databases is an important step in the early stages of drug development. It is based on the similarity principle and is used to reduce the chemical space of large databases to a manageable size where chosen ligands can be experimentally tested. Ligand-based virtual screening can also be used to identify bioactive molecules with different basic scaffolds compared to already known bioactive molecules, thus having the potential to increase the structural variability of compounds. Here, we present an interface between the popular molecular graphics system PyMOL and the ligand-based virtual screening software LiSiCA available at http://insilab.org/lisica-plugin and demonstrate how this interface can be used in the early stages of drug discovery process.
Keywords: LiSiCa, PyMOL, informatics, applications
Published in DKUM: 27.06.2017; Views: 1251; Downloads: 367
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