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  1. Article ; Online: In silico study of the structurally similar ORL1 receptor agonist and antagonist pairs reveal possible mechanism of receptor activation.

    Senćanski, Milan / Dosen-Mićović, Ljiljana

    The protein journal

    2014  Volume 33, Issue 3, Page(s) 231–242

    Abstract: An opioid receptor like (ORL1) receptor is a member of a family of G-protein coupled receptors. It is anew pharmaceutical target with broad therapeutic potential in the regulation of important biological functions such as nociception, mood disorders, ... ...

    Abstract An opioid receptor like (ORL1) receptor is a member of a family of G-protein coupled receptors. It is anew pharmaceutical target with broad therapeutic potential in the regulation of important biological functions such as nociception, mood disorders, drug abuse, learning or cardiovascular control. The crystal structure of this receptor in complex with an antagonist was determined recently (PDBID: 4EA3). By removing the ligand and subjecting the empty receptor to molecular dynamics simulation in a solvated lipid membrane we obtained an optimized ORL1 receptor structure which could be used in a subsequent docking study of two structurally similar agonist–antagonist ligand pairs. Ligands were docked to the empty ORL1 receptor (with and without the third intracellular loop, IC3)in different orientations, and the resulting complexes were monitored during molecular dynamics simulation in order to see how the subtle differences in structure of agonists and antagonists might affect ligand–receptor interactions and trigger receptor activation. It was established that agonists and antagonists bound to the same, relatively large, binding site in the receptor, created by residues from transmembrane helices TM2, TM3, TM5, TM6 and TM7 and close to the extra cellular end of the receptor bundle.The key difference between these two types of ligands is interaction with residue Val283(6.55) and a flexibility of ligand molecules. Ligands that cannot easily avoid this interaction will initiate movement of the intracellular end of TM6 (by a mechanism which involves Met134(3.36) and several amino acids of TM5) and possibly activate the receptor when assisted by G-protein.
    MeSH term(s) Binding Sites ; Computer Simulation ; Molecular Dynamics Simulation ; Narcotic Antagonists/chemistry ; Narcotic Antagonists/metabolism ; Receptors, Opioid/agonists ; Receptors, Opioid/chemistry ; Receptors, Opioid/metabolism
    Chemical Substances Narcotic Antagonists ; Receptors, Opioid ; nociceptin receptor (DVO6VKD7IJ)
    Language English
    Publishing date 2014-03-22
    Publishing country Netherlands
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2143071-8
    ISSN 1875-8355 ; 1572-3887
    ISSN (online) 1875-8355
    ISSN 1572-3887
    DOI 10.1007/s10930-014-9555-0
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Molecular modelling of fentanyl analogs

    Došen-Mićović Ljiljana I.

    Journal of the Serbian Chemical Society, Vol 69, Iss 11, Pp 843-

    2004  Volume 854

    Abstract: Fentanyl is a highly potent and clinically widely used narcotic analgesic. A large number of its analogs have been synthesized, some of which (sufentanil and alfentanyl) are also in clinical use. Theoretical studies, in recent years, afforded a better ... ...

    Abstract Fentanyl is a highly potent and clinically widely used narcotic analgesic. A large number of its analogs have been synthesized, some of which (sufentanil and alfentanyl) are also in clinical use. Theoretical studies, in recent years, afforded a better understanding of the structure-activity relationships of this class of opiates and allowed insight into the molecular mechanism of the interactions of fentanyl analogs with their receptors. An overview of the current computational techniques for modeling fentanyl analogs, their receptors and ligand-receptor interactions is presented in this paper.
    Keywords fentanyl analogs ; molecular modeling ; μ-receptor ; ligand-receptor interactions ; Chemistry ; QD1-999
    Language English
    Publishing date 2004-01-01T00:00:00Z
    Publisher Serbian Chemical Society
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Location of the hydrophobic pocket in the binding site of fentanyl analogs in the µ-opioid receptor

    Došen-Mićović Ljiljana / Ivanović Milovan / Mićović Vuk

    Journal of the Serbian Chemical Society, Vol 72, Iss 7, Pp 643-

    2007  Volume 654

    Abstract: Fentanyl is a highly potent and clinically widely used narcotic analgesic. The synthesis of its analogs remains a challenge in an attempt to develop highly selective µ-opioid receptor agonists with specific pharmacological properties. In this paper, the ... ...

    Abstract Fentanyl is a highly potent and clinically widely used narcotic analgesic. The synthesis of its analogs remains a challenge in an attempt to develop highly selective µ-opioid receptor agonists with specific pharmacological properties. In this paper, the use of flexible molecular docking of several specific fentanyl analogs to the µ-opioid receptor model, in order to test the hypothesis that the hydrophobic pocket accommodates alkyl groups at position 3 of the fentanyl skeleton, is described. The stereoisomers of the following compounds were studied: cis- and trans-3-methylfentanyl, 3,3-dimethylfentanyl, cis- and trans-3-ethylfentanyl, cis- and trans-3-propylfentanyl, cis-3-isopropylfentanyl and cis-3-benzylfentanyl. The optimal position and orientation of these fentanyl analogs in the binding pocket of the µ-receptor, explaining their enantiospecific potency, were determined. It was found that the 3-alkyl group of cis-3R,4S and trans-3S,4S stereoisomers of all the active compounds occupies the hydrophobic pocket between TM5, TM6 and TM7, made up of the amino acids Trp318 (TM7), Ile322 (TM7), Ile301 (TM6) and Phe237 (TM5). However, the fact that this hydrophobic pocket can also accommodate the bulky 3-alkyl substituents of the two inactive compounds: cis-3-isopropylfentanyl, and cis-3-benzylfentanyl, indicates that this hydrophobic pocket in the employed receptor model is probably too large. .
    Keywords molecular modeling ; fentanyl analogs ; ligand-receptor interactions ; docking simulation ; Chemistry ; QD1-999
    Subject code 540
    Language English
    Publishing date 2007-01-01T00:00:00Z
    Publisher Serbian Chemical Society
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: Molecular modeling of 5HT2A receptor - arylpiperazine ligands interactions.

    Sencanski, Milan / Sukalovic, Vladimir / Shakib, Kaveh / Soskic, Vukic / Dosen-Micovic, Ljiljana / Kostic-Rajacic, Sladjana

    Chemical biology & drug design

    2014  Volume 83, Issue 4, Page(s) 462–471

    Abstract: In this paper, we report the molecular modeling of the 5HT2A receptor and the molecular docking of arylpiperazine-like ligands. The focus of the research was on explaining the effects the ligand structure has on the binding properties of the 5HT2A ... ...

    Abstract In this paper, we report the molecular modeling of the 5HT2A receptor and the molecular docking of arylpiperazine-like ligands. The focus of the research was on explaining the effects the ligand structure has on the binding properties of the 5HT2A receptor and on the key interactions between the ligands and the receptor-binding site. To see what the receptor–ligand interactions were, various substituents were introduced in one part of the ligand, keeping the rest unchanged. In this way, using a docking analysis on the proposed 5HT2A receptor model, we identified key receptor–ligand interactions and determined their properties. Those properties were correlated with experimentally determined binding affinities in order to determine the structure to activity relationship of the examined compounds.
    MeSH term(s) Binding Sites ; Ligands ; Models, Molecular ; Molecular Docking Simulation ; Piperazines/chemistry ; Protein Binding ; Receptor, Serotonin, 5-HT2A/chemistry
    Chemical Substances Ligands ; Piperazines ; Receptor, Serotonin, 5-HT2A
    Language English
    Publishing date 2014-04-18
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2216600-2
    ISSN 1747-0285 ; 1747-0277
    ISSN (online) 1747-0285
    ISSN 1747-0277
    DOI 10.1111/cbdd.12261
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: Docking studies suggest ligand-specific δ-opioid receptor conformations

    Micovic, Vuk / Ivanovic, Milovan D / Dosen-Micovic, Ljiljana

    Journal of molecular modeling. 2009 Mar., v. 15, no. 3

    2009  

    Abstract: An automated docking procedure was used to study binding of a series of δ-selective ligands to three models of the δ-opioid receptor. These models are thought to represent the three ligand-specific receptor conformations. Docking results are in agreement ...

    Abstract An automated docking procedure was used to study binding of a series of δ-selective ligands to three models of the δ-opioid receptor. These models are thought to represent the three ligand-specific receptor conformations. Docking results are in agreement with point mutation studies and suggest that different ligands--agonists and antagonists--may bind to the same binding site under different receptor conformations. Docking to different receptor models (conformations) also suggests that by changing to a receptor-specific conformation, the receptor may open or close different binding sites to other ligands. [graphic removed]
    Language English
    Dates of publication 2009-03
    Size p. 267-280.
    Publisher Springer-Verlag
    Publishing place Berlin/Heidelberg
    Document type Article
    ISSN 0949-183X
    DOI 10.1007/s00894-008-0396-7
    Database NAL-Catalogue (AGRICOLA)

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  6. Article: Synthesis of Orthogonally Protected (±)-3-Amino-4-anilidopiperidines and (±)-3-N-Carbomethoxyfentanyl

    Jevtić, Ivana I. / Došen-Mićović, Ljiljana I. / Ivanović, Evica R. / Todorović, Nina M. / Ivanović, Milovan D.

    Synthesis

    2017  Volume 49, Issue 14, Page(s) 3126–3136

    Abstract: The synthesis of orthogonally protected cis - and trans -3-amino-4-anilidopiperidine derivatives has been accomplished in six steps, starting from readily accessible 4-piperidone derivatives. The last three steps, i.e., N-acylation, Hofmann ... ...

    Abstract The synthesis of orthogonally protected cis - and trans -3-amino-4-anilidopiperidine derivatives has been accomplished in six steps, starting from readily accessible 4-piperidone derivatives. The last three steps, i.e., N-acylation, Hofmann rearrangement, and carbamate cleavage, involved separated (±)- cis and (±)- trans intermediates. Complete retention of configuration was observed at position 3 of the piperidine ring. Specifically protected positions 1 and 3 at the piperidine scaffold allow for selective deprotection and introduction of diverse substituents at the respective nitrogen sites. The orthogonally protected anilidopiperidines open avenues to potentially pharmacologically active compounds, including opioids and various bivalent ligands for G protein-coupled receptors. In addition, a prototype of a novel class of fentanyl derivatives, possessing a 3-amino group, was synthesized by using the same approach.
    Keywords heterocycles ; rearrangement ; acylation ; protecting groups ; diastereoselectivity
    Language English
    Publishing date 2017-04-03
    Publisher © Georg Thieme Verlag
    Publishing place Stuttgart ; New York
    Document type Article
    ZDB-ID 2033062-5
    ISSN 1437-210X ; 0039-7881
    ISSN (online) 1437-210X
    ISSN 0039-7881
    DOI 10.1055/s-0036-1588985
    Database Thieme publisher's database

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  7. Article ; Online: Structural requirements for ligands of the δ-opioid receptor

    Mićović Vuk I. / Ivanović Milovan D. / Došen-Mićović Ljiljana

    Journal of the Serbian Chemical Society, Vol 74, Iss 11, Pp 1207-

    2009  Volume 1217

    Abstract: The δ-opioid receptor is sensitive to ligand geometry. In order to assist the synthesis of new δ-selective opioid ligands, the structure elements of δ-selective opioid ligands necessary for their effective binding were investigated. The automated docking ...

    Abstract The δ-opioid receptor is sensitive to ligand geometry. In order to assist the synthesis of new δ-selective opioid ligands, the structure elements of δ-selective opioid ligands necessary for their effective binding were investigated. The automated docking procedure with a flexible ligand was used to simulate the binding of 17 δ-selective ligands to the δ-receptor. It was found that voluminous N-alkyl groups reduce the binding potency of naltrindole derivatives by preventing the ligands from adopting the preferred conformation in the receptor. This was confirmed by enantiospecific binding of chiral compounds where only one enantiomer adopts the naltrindole-like preferred conformation in the binding pocket. Voluminous groups replacing the hydroxyl group in the 3-hydroxybenzyl fragment of naltrindole analogs reduce the binding potency due to unfavorable steric interactions with the receptor. The two diastereoisomers of the potent δ-opioid ligand SNC80 confirmed the preferred binding conformation and the major receptor-ligand interactions.
    Keywords molecular modeling ; δ-opioid receptor ; ligand-receptor interactions ; docking simulation ; Chemistry ; QD1-999
    Subject code 540
    Language English
    Publishing date 2009-01-01T00:00:00Z
    Publisher Serbian Chemical Society
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article ; Online: Docking studies suggest ligand-specific delta-opioid receptor conformations.

    Micovic, Vuk / Ivanovic, Milovan D / Dosen-Micovic, Ljiljana

    Journal of molecular modeling

    2008  Volume 15, Issue 3, Page(s) 267–280

    Abstract: An automated docking procedure was used to study binding of a series of delta-selective ligands to three models of the delta-opioid receptor. These models are thought to represent the three ligand-specific receptor conformations. Docking results are in ... ...

    Abstract An automated docking procedure was used to study binding of a series of delta-selective ligands to three models of the delta-opioid receptor. These models are thought to represent the three ligand-specific receptor conformations. Docking results are in agreement with point mutation studies and suggest that different ligands--agonists and antagonists--may bind to the same binding site under different receptor conformations. Docking to different receptor models (conformations) also suggests that by changing to a receptor-specific conformation, the receptor may open or close different binding sites to other ligands.
    MeSH term(s) Binding Sites ; Ligands ; Models, Molecular ; Protein Conformation ; Receptors, Opioid, delta/antagonists & inhibitors ; Receptors, Opioid, delta/chemistry ; Receptors, Opioid, delta/metabolism ; Structure-Activity Relationship ; Thermodynamics
    Chemical Substances Ligands ; Receptors, Opioid, delta
    Language English
    Publishing date 2008-12-04
    Publishing country Germany
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1284729-X
    ISSN 0948-5023 ; 1610-2940
    ISSN (online) 0948-5023
    ISSN 1610-2940
    DOI 10.1007/s00894-008-0396-7
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Calorimetric and spectroscopic studies of aminoglycoside binding to AT-rich DNA triple helices.

    Xi, Hongjuan / Kumar, Sunil / Dosen-Micovic, Ljiljana / Arya, Dev P

    Biochimie

    2010  Volume 92, Issue 5, Page(s) 514–529

    Abstract: Calorimetric and fluorescence techniques were used to characterize the binding of aminoglycosides-neomycin, paromomycin, and ribostamycin, with 5'-dA(12)-x-dT(12)-x-dT(12)-3' intramolecular DNA triplex (x = hexaethylene glycol) and poly(dA).2poly(dT) ... ...

    Abstract Calorimetric and fluorescence techniques were used to characterize the binding of aminoglycosides-neomycin, paromomycin, and ribostamycin, with 5'-dA(12)-x-dT(12)-x-dT(12)-3' intramolecular DNA triplex (x = hexaethylene glycol) and poly(dA).2poly(dT) triplex. Our results demonstrate the following features: (1) UV thermal analysis reveals that the T(m) for triplex decreases with increasing pH value in the presence of neomycin, while the T(m) for the duplex remains unchanged. (2) The binding affinity of neomycin decreases with increased pH, although there is an increase in observed binding enthalpy. (3) ITC studies conducted in two buffers (sodium cacodylate and MOPS) yield the number of protonated drug amino groups (Deltan) as 0.29 and 0.40 for neomycin and paromomycin interaction with 5'-dA(12)-x-dT(12)-x-dT(12)-3', respectively. (4) The specific heat capacity change (DeltaC(p)) determined by ITC studies is negative, with more negative values at lower salt concentrations. From 100 mM to 250 mM KCl, the DeltaC(p) ranges from -402 to -60 cal/(mol K) for neomycin. At pH 5.5, a more positive DeltaC(p) is observed, with a value of -98 cal/(mol K) at 100 mM KCl. DeltaC(p) is not significantly affected by ionic strength. (5) Salt dependence studies reveal that there are at least three amino groups of neomycin participating in the electrostatic interactions with the triplex. (6) FID studies using thiazole orange were used to derive the AC(50) (aminoglycoside concentration needed to displace 50% of the dye from the triplex) values. Neomycin shows a seven fold higher affinity than paromomycin and eleven fold higher affinity than ribostamycin at pH 6.8. (7) Modeling studies, consistent with UV and ITC results, show the importance of an additional positive charge in triplex recognition by neomycin. The modeling and thermodynamic studies indicate that neomycin binding to the DNA triplex depends upon significant contributions from charge as well as shape complementarity of the drug to the DNA triplex Watson-Hoogsteen groove.
    MeSH term(s) Aminoglycosides/metabolism ; Calorimetry/methods ; Circular Dichroism ; DNA/metabolism ; Hydrogen-Ion Concentration ; Models, Molecular ; Osmolar Concentration ; Potassium Chloride/chemistry ; Protein Denaturation ; Spectrometry, Fluorescence/methods ; Spectrophotometry, Ultraviolet/methods
    Chemical Substances Aminoglycosides ; Potassium Chloride (660YQ98I10) ; DNA (9007-49-2)
    Language English
    Publishing date 2010-02-16
    Publishing country France
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 120345-9
    ISSN 1638-6183 ; 0300-9084
    ISSN (online) 1638-6183
    ISSN 0300-9084
    DOI 10.1016/j.biochi.2010.02.004
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article: Hofmann Rearrangement of Carboxamides Mediated by N-Bromo­acetamide

    Jevtić, Ivana I. / Došen-Mićović, Ljiljana / Ivanović, Evica R. / Ivanović, Milovan D.

    Synthesis

    2016  Volume 48, Issue 10, Page(s) 1550–1560

    Abstract: An efficient, one-pot procedure for the Hofmann rearrangement of aromatic and aliphatic amides has been developed. Methyl and benzyl carbamates are produced with N -bromoacetamide in the presence of lithium hydroxide or lithium methoxide, in high yields. ...

    Abstract An efficient, one-pot procedure for the Hofmann rearrangement of aromatic and aliphatic amides has been developed. Methyl and benzyl carbamates are produced with N -bromoacetamide in the presence of lithium hydroxide or lithium methoxide, in high yields. β-Phenylamino amides gave five-membered cyclic ureas stereospecifically. Side products of aryl or benzyl bromination were minimized. This procedure offers an easy access to various protected amines or diamines, which represent important synthetic precursors.
    Keywords Hofmann rearrangement ; amides ; stereoselectivity ; cyclization ; heterocycles
    Language German
    Publishing date 2016-03-11
    Publisher © Georg Thieme Verlag
    Publishing place Stuttgart ; New York
    Document type Article
    ZDB-ID 2033062-5
    ISSN 1437-210X ; 0039-7881
    ISSN (online) 1437-210X
    ISSN 0039-7881
    DOI 10.1055/s-0035-1561405
    Database Thieme publisher's database

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