Publications by authors named "Agnes Richard"

19 Publications

  • Page 1 of 1

Molecular Imaging of Tumors Using a Quantitative T 1 Mapping Technique via Magnetic Resonance Imaging.

Diagnostics (Basel) 2015 ;5(3):318-32

Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA ; Department of Molecular Biology and Microbiology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA.

Magnetic resonance imaging (MRI) of glioblastoma multiforme (GBM) with molecular imaging agents would allow for the specific localization of brain tumors. Prior studies using T 1-weighted MR imaging demonstrated that the SBK2-Tris-(Gd-DOTA)3 molecular imaging agent labeled heterotopic xenograft models of brain tumors more intensely than non-specific contrast agents using conventional T 1-weighted imaging techniques. In this study, we used a dynamic quantitative T 1 mapping strategy to more objectively compare intra-tumoral retention of the SBK2-Tris-(Gd-DOTA)3 agent over time in comparison to non-targeted control agents. Our results demonstrate that the targeted SBK2-Tris-(Gd-DOTA)3 agent, a scrambled-Tris-(Gd-DOTA)3 control agent, and the non-specific clinical contrast agent Optimark(™) all enhanced flank tumors of human glioma cells with similar maximal changes on T 1 mapping. However, the retention of the agents differs. The non-specific agents show significant recovery within 20 min by an increase in T 1 while the specific agent SBK2-Tris-(Gd-DOTA)3 is retained in the tumors and shows little recovery over 60 min. The retention effect is demonstrated by percent change in T 1 values and slope calculations as well as by calculations of gadolinium concentration in tumor compared to muscle. Quantitative T 1 mapping demonstrates the superior binding and retention in tumors of the SBK2-Tris-(Gd-DOTA)3 agent over time compared to the non-specific contrast agent currently in clinical use.
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http://dx.doi.org/10.3390/diagnostics5030318DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4589153PMC
February 2016

Peptide-Targeted Gold Nanoparticles for Photodynamic Therapy of Brain Cancer.

Part Part Syst Charact 2015 Apr;32(4):448-457

Departments of Biomedical Engineering and Radiology, NFCR Center for Molecular Imaging, Case Western Reserve University, 11100 Euclid Ave., Cleveland, OH 44106, USA.

Targeted drug delivery using epidermal growth factor peptide-targeted gold nanoparticles (EGF-Au NPs) is investigated as a novel approach for delivery of photodynamic therapy (PDT) agents, specifically Pc 4, to cancer. In vitro studies of PDT show that EGF-Au NP-Pc 4 is twofold better at killing tumor cells than free Pc 4 after increasing localization in early endosomes. In vivo studies show that targeting with EGF-Au NP-Pc 4 improves accumulation of fluorescence of Pc 4 in subcutaneous tumors by greater than threefold compared with untargeted Au NPs. Targeted drug delivery and treatment success can be imaged via the intrinsic fluorescence of the PDT drug Pc 4. Using Pc 4 fluorescence, it is demonstrated in vivo that EGF-Au NP-Pc 4 impacts biodistribution of the NPs by decreasing the initial uptake by the reticuloendothelial system (RES) and by increasing the amount of Au NPs circulating in the blood 4 h after IV injection. Interestingly, in vivo PDT with EGF-Au NP-Pc 4 results in interrupted tumor growth when compared with EGF-Au NP control mice when selectively activated with light. These data demonstrate that EGF-Au NP-Pc 4 utilizes cancer-specific biomarkers to improve drug delivery and therapeutic efficacy over untargeted drug delivery.
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http://dx.doi.org/10.1002/ppsc.201400119DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4437573PMC
April 2015

An optical probe for noninvasive molecular imaging of orthotopic brain tumors overexpressing epidermal growth factor receptor.

Mol Cancer Ther 2012 Oct 17;11(10):2202-11. Epub 2012 Jul 17.

Departments of Radiology, Biomedical Engineering, and Pathology, NFCR Center for Molecular Imaging at Case, Case Western Reserve University, Wearn Building, Room B-42, 11100 Euclid Avenue, Cleveland, OH 44106, USA.

We have developed a near-infrared (NIR) probe that targets cells overexpressing the EGF receptor (EGFR) for imaging glioblastoma brain tumors in live subjects. A peptide specific for the EGFR was modified with various lengths of monodiscrete polyethylene glycol (PEG) units and a NIR Cy5.5 fluorescence dye. The lead compound, compound 2, with one unit of PEG displayed good binding (8.9 μmol/L) and cellular uptake in glioblastoma cells overexpressing EGFR in vitro. The in vivo studies have shown that the probe was able to selectively label glioblastoma-derived orthotopic brain tumors. In vivo image analyses of peptide binding to the tumors using fluorescence-mediated molecular tomography revealed that the compound could distinguish between tumors expressing different levels of EGFR. The data presented here represent the first demonstration of differential quantitation of tumors expressing EGFR in live animals by a targeted NIR fluorescence probe using a molecular imaging device.
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http://dx.doi.org/10.1158/1535-7163.MCT-12-0211DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3829608PMC
October 2012

Addressing brain tumors with targeted gold nanoparticles: a new gold standard for hydrophobic drug delivery?

Small 2011 Aug 1;7(16):2301-6. Epub 2011 Jun 1.

Department of Chemistry, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA, Fax: (+1) 216-368-3006.

EGF-modified Au NP-Pc 4 conjugates showed 10-fold improved selectivity to the brain tumor compared to untargeted conjugates. The hydrophobic photodynamic therapy drug Pc 4 can be delivered efficiently into glioma brain tumors by EGF peptide-targeted Au NPs. Compared to the untargeted conjugates, EGF-Au NP-Pc 4 conjugates showed 10-fold improved selectivity to the brain tumor. This delivery system holds promise for future delivery of a wider range of hydrophobic therapeutic drugs for the treatment of hard-to-reach cancers.
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http://dx.doi.org/10.1002/smll.201100628DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3837553PMC
August 2011

Novel peptide ligands with dual acting pharmacophores designed for the pathophysiology of neuropathic pain.

Brain Res 2011 Jun 20;1395:1-11. Epub 2011 Apr 20.

Department of Pharmacology, University of Arizona Health Sciences Center, P.O. Box 245050, 1501 N Campbell Ave., Tucson, AZ 85724, USA.

The conventional design of high affinity drugs targeted to a single molecule has not resulted in clinically useful therapies for pain relief. Recent reviews have suggested that newly designed analgesic drugs should incorporate multiple targets. The distributions of cholecystokinin (CCK) and CCK receptors in the central nervous system (CNS) overlap significantly with endogenous opioid systems and can be dually targeted. CCK has been shown to act as an endogenous "anti-analgesic" peptide and neuropathic pain conditions promote endogenous CCK release in CNS regions of pain modulation. Administration of CCK into nuclei of the rostral ventromedial medulla induces pronociceptive behaviors in rats. RSA 504 and RSA 601 are novel bifunctional compounds developed to target neuropathic pain by simultaneously acting as agonists at two distinct opioid receptors and antagonizing CCK receptors in the CNS. RSA 504 and RSA 601 demonstrate agonist activity in vitro and antihypersensitivity to mechanical and thermal stimuli in vivo using the spinal nerve ligation model of neuropathic pain. Intrathecal administration of RSA 504 and RSA 601 did not demonstrate antinociceptive tolerance over 7 days of administration and did not display motor impairment or sedation using a rotarod. These are the first behavioral studies that demonstrate how multi-targeted molecule design can address the pathology of neuropathic pain. These compounds with δ and μ opioid agonist activity and CCK antagonist activity within one molecule offer a novel approach with efficacy for neuropathic pain while lacking the side effects typically caused by conventional opioid therapies.
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http://dx.doi.org/10.1016/j.brainres.2011.04.024DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3105124PMC
June 2011

Suborganelle sensing of mitochondrial cAMP-dependent protein kinase activity.

J Am Chem Soc 2010 May;132(17):6075-80

Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA.

A fluorescent sensor of protein kinase activity has been developed and used to characterize the compartmentalized location of cAMP-dependent protein kinase activity in mitochondria. The sensor functions via a phosphorylation-induced release of a quencher from a peptide-based substrate, producing a 150-fold enhancement in fluorescence. The quenching phenomenon transpires via interaction of the quencher with Arg residues positioned on the peptide substrate. Although the cAMP-dependent protein kinase is known to be present in mitochondria, the relative amount of enzyme positioned in the major compartments (outer membrane, intermembrane space, and the matrix) of the organelle is unclear. The fluorescent sensor developed in this study was used to reveal the relative matrix/intermembrane space/outer membrane (85:6:9) distribution of PKA in bovine heart mitochondria.
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http://dx.doi.org/10.1021/ja909652qDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2862470PMC
May 2010

Real-world emission factors for antimony and other brake wear related trace elements: size-segregated values for light and heavy duty vehicles.

Environ Sci Technol 2009 Nov;43(21):8072-8

Empa, Swiss Federal Laboratories for Materials Testing and Research, CH-8600 Duebendorf, Switzerland.

Hourly trace element measurements were performed in an urban street canyon and next to an interurban freeway in Switzerland during more than one month each, deploying a rotating drum impactor (RDI) and subsequent sample analysis by synchrotron radiation X-ray fluorescence spectrometry (SR-XRF). Antimony and other brake wear associated elements were detected in three particle size ranges (2.5-10, 1-2.5, and 0.1-1 microm). The hourly measurements revealed that the effect of resuspended road dust has to be taken into account for the calculation of vehicle emission factors. Individual values for light and heavy duty vehicles were obtained for stop-and-go traffic in the urban street canyon. Mass based brake wear emissions were predominantly found in the coarse particle fraction. For antimony, determined emission factors were 11 +/- 7 and 86 +/- 42 microg km(-1) vehicle(-1) for light and heavy duty vehicles, respectively. Antimony emissions along the interurban freeway with free-flowing traffic were significantly lower. Relative patterns for brake wear related elements were very similar for both considered locations. Beside vehicle type specific brake wear emissions, road dust resuspension was found to be a dominant contributor of antimony in the street canyon.
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http://dx.doi.org/10.1021/es9006096DOI Listing
November 2009

Neuropathic pain is maintained by brainstem neurons co-expressing opioid and cholecystokinin receptors.

Brain 2009 Mar 2;132(Pt 3):778-87. Epub 2008 Dec 2.

Department of Pharmacology, University of Arizona, Tucson, AZ 85724, USA.

Descending input from the rostral ventromedial medulla (RVM) provides positive and negative modulation of spinal nociceptive transmission and has been proposed to be critical for maintaining neuropathic pain. This study tests the hypothesis that neuropathic pain requires the activity of a subset of RVM neurons that are distinguished by co-expression of mu opioid receptor (MOR) and cholecystokinin type 2 receptor (CCK2). Using male Sprague-Dawley rats, we demonstrate that discrete RVM neurons express MOR and CCK2; over 80% of these cells co-express both receptors. Agonist-directed cell lesion in the RVM with the cytotoxin, saporin, using either CCK-saporin to target CCK receptor expressing cells, or dermorphin-saporin to target MOR expressing cells, resulted in concomitant loss of CCK2 and MOR expressing cells, did not alter the basal sensory thresholds but abolished the hyperalgesia induced by microinjection of CCK into the RVM. The findings suggest that these CCK2-MOR co-expressing RVM neurons facilitate pain and can be directly activated by CCK input to the RVM. Furthermore, lesion of these RVM neurons did not affect the initial development of neuropathic pain in the hind paw upon injury to the sciatic nerve, but the abnormal pain states were short lived such that by about day 9 the sensory thresholds had reverted to pre-injury baselines despite the existing neuropathy. These data support our hypothesis and identify CCK2-MOR co-expressing neurons in the RVM as potential therapeutic targets for neuropathic pain.
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http://dx.doi.org/10.1093/brain/awn330DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2724921PMC
March 2009

Structure-activity relationships of bifunctional cyclic disulfide peptides based on overlapping pharmacophores at opioid and cholecystokinin receptors.

Peptides 2008 Aug 10;29(8):1413-23. Epub 2008 Apr 10.

Department of Chemistry, University of Arizona, Tucson, AZ 85721, USA.

Prolonged opioid exposure increases the expression of cholecystokinin (CCK) and its receptors in the central nervous system (CNS), where CCK may attenuate the antinociceptive effects of opioids. The complex interactions between opioid and CCK may play a role in the development of opioid tolerance. We designed and synthesized cyclic disulfide peptides and determined their agonist properties at opioid receptors and antagonist properties at CCK receptors. Compound 1 (Tyr-c[d-Cys-Gly-Trp-Cys]-Asp-Phe-NH(2)) showed potent binding and agonist activities at delta and mu opioid receptors but weak binding to CCK receptors. The NMR structure of the lead compound displayed similar conformational features of opioid and CCK ligands.
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http://dx.doi.org/10.1016/j.peptides.2008.03.022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2601673PMC
August 2008

Opioid and melanocortin receptors: do they have overlapping pharmacophores?

Biopolymers 2008 ;90(3):433-8

Department of Chemistry, University of Arizona, Tucson, AZ 85721, USA.

We have identified compound 1 as a novel ligand for opioid and melanocortin (MC) receptors, which is derived from the overlapping of a well known structure for the delta opioid receptor, 2,6-dimethyltyrosine (Dmt)-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (Tic), and a small molecule for the MC receptor, Tic-DPhe(p-Cl)-piperidin-4-yl-N-phenyl-propionamide. Ligand 1 showed that there is an overlapping pharmacophore between opioid and MC receptors through the Tic residue. The ligand displayed high biological activities at the delta opioid receptor (Ki = 0.38 nM in binding assay, EC(50) = 0.48 nM in GTP-gamma-S binding assay, IC(50) = 74 nM in MVD) as an agonist instead of an antagonist and showed selective binding affinity (IC(50) = 2.3 muM) at the MC-3 receptor rather than at the MC-5 receptor. A study of the structure-activity relationships demonstrated that the residues in positions 2, 3, and the C-terminus act as a pharmacophore for the MC receptors, and the residues in positions 1 and 2 act as a pharmacophore for the opioid receptors. Thus, this structural construct can be used to prepare chimeric structures with adjacent or overlapping pharmacophores for opioid and MC receptors.
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http://dx.doi.org/10.1002/bip.20814DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2693099PMC
July 2008

Photochemically-activated probes of protein-protein interactions.

Org Lett 2007 Jun 17;9(12):2249-52. Epub 2007 May 17.

Department of Biochemistry, The Albert Einstein College of Medicine of Yeshiva University, 1300 Morris Park Avenue, Bronx, New York 10461-1602, USA.

The activity of light-activatable ("caged") compounds can be temporally and spatially controlled, thereby providing a means to interrogate intracellular biochemical pathways as a function of time and space. Nearly all caged peptides contain photocleavable groups positioned on the side chains of key residues. We describe an alternative active site targeted strategy that disrupts the interaction between the protein target (SH2 domain, kinase, and proteinase) and a critical amide NH moiety of the peptide probe.
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http://dx.doi.org/10.1021/ol070238tDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3057037PMC
June 2007

Understanding the structural requirements of 4-anilidopiperidine analogues for biological activities at mu and delta opioid receptors.

Bioorg Med Chem Lett 2007 Apr 8;17(8):2161-5. Epub 2007 Feb 8.

Department of Chemistry, University of Arizona, Tucson, AZ 85721, USA.

New 4-anilidopiperidine analogues in which the phenethyl group of fentanyl was replaced by several aromatic ring-contained amino acids (or acids) were synthesized to study the biological effect of the substituents on mu and delta opioid receptor interactions. These analogues showed broad (47 nM-76 microM) but selective (up to 17-fold) binding affinities at the mu opioid receptor over the delta opioid receptor, as predicted from the message-address concept.
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http://dx.doi.org/10.1016/j.bmcl.2007.01.114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2274923PMC
April 2007

Deep quench: an expanded dynamic range for protein kinase sensors.

J Am Chem Soc 2007 Mar 17;129(10):2742-3. Epub 2007 Feb 17.

Department of Biochemistry, The Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA.

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http://dx.doi.org/10.1021/ja068280rDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2517079PMC
March 2007

Partial retro-inverso, retro, and inverso modifications of hydrazide linked bifunctional peptides for opioid and cholecystokinin (CCK) receptors.

J Med Chem 2007 Jan;50(1):165-8

Department of Chemistry, University of Arizona, Tucson, Arizona 85721, USA.

Partially modified retro-inverso, retro, and inverso isomers of hydrazide linked bifunctional peptides were designed, synthesized, and evaluated for bioactivities at delta/mu opioid receptors and CCK-1/CCK-2 receptors. All modifications of the CCK pharmacophore moiety affected bioactivities for the CCK-1 and CCK-2 receptors (up to 180-fold increase in the binding affinity with higher selectivity) and for the delta and mu opioid receptors. The results indicate that the opioid and CCK pharmacophores in one molecule interact with each other to induce topographical changes for both pharmacophores.
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http://dx.doi.org/10.1021/jm061268pDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2365893PMC
January 2007

New paradigms and tools in drug design for pain and addiction.

AAPS J 2006 Jul 14;8(3):E450-60. Epub 2006 Jul 14.

Department of Chemistry, University of Arizona, Tucson, AZ 85721, USA.

New modalities providing safe and effective treatment of pain, especially prolonged pathological pain, have not appeared despite much effort. In this mini-review/overview we suggest that new paradigms of drug design are required to counter the underlying changes that occur in the nervous system that may elicit chronic pain states. We illustrate this approach with the example of designing, in a single ligand, molecules that have agonist activity at mu and delta opioid receptors and antagonist activities at cholecystokinin (CCK) receptors. Our findings thus far provide evidence in support of this new approach to drug design. We also report on a new biophysical method, plasmon waveguide resonance (PWR) spectroscopy, which can provide new insights into information transduction in G-protein coupled receptors (GPCRs) as illustrated by the delta opioid receptor.
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http://dx.doi.org/10.1208/aapsj080353DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1764851PMC
July 2006

Structure-activity relationships of bifunctional peptides based on overlapping pharmacophores at opioid and cholecystokinin receptors.

J Med Chem 2006 May;49(10):2868-75

Departments of Chemistry and Pharmacology, University of Arizona, Tucson, Arizona 85721, USA.

Cholecystokinin (CCK) has been identified as a pronociceptive endogenous peptide which also possesses antiopioid actions. CCK may be upregulated in conditions of chronic pain or during sustained morphine administration resulting in attenuation of opioid-mediated pain relief. These complex interactions between opioids and endogenous CCK receptor systems have suggested the need for a new paradigm in drug design for some states of chronic pain. In these circumstances the rational design of potential drugs for the treatment of these conditions must be based on one ligand for multiple targets. We have designed a single peptide which can interact with delta and mu opioid receptors as agonists and with CCK receptors as antagonists. The ligands were designed based on a model of overlapping pharmacophores of opioid and CCK peptide ligands, which incorporates opioid pharmacophores at the N-terminal and CCK tetrapeptide pharmacophores at the C-terminal of the designed ligands. We measured binding and activities of our bifunctional peptides at opioid and CCK receptors. Compound 11 (Tyr-d-Ala-Gly-d-Trp-NMeNle-Asp-Phe-NH(2)) demonstrated opioid agonist properties at delta and mu receptors (IC(50) = 63 +/- 27 nM and 150 +/- 65 nM, respectively in MVD and GPI tissue assays) and high binding affinity at CCK-1 and CCK-2 receptors (K(i) = 320 and 1.5 nM, respectively). Compound 9 (Tyr-d-Nle-Gly-Trp-Nle-Asp-Phe-NH(2)) displayed potent agonist activity at delta and mu receptors (IC(50) = 23 +/-10 nM and 210 +/- 52 nM, respectively in MVD and GPI tissue assays), with a balanced binding affinity for CCK-1 and CCK-2 receptors (K(i) = 9.6 and 15 nM, respectively). These results provide evidence supporting the concept that opioid and CCK receptors have overlapping pharmacophores required for binding affinity and biological activity and that designing overlapping pharmacophores of two peptides into a single peptide is a valid drug design approach.
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http://dx.doi.org/10.1021/jm050921qDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1484468PMC
May 2006

Design and synthesis of novel hydrazide-linked bifunctional peptides as delta/mu opioid receptor agonists and CCK-1/CCK-2 receptor antagonists.

J Med Chem 2006 Mar;49(5):1773-80

Department of Chemistry, University of Arizona, Tucson, Arizona 85721, USA.

A series of hydrazide-linked bifunctional peptides designed to act as agonists for delta/mu opioid receptors and antagonists for CCK-1/CCK-2 receptors was prepared and tested for binding to both opioid and CCK receptors and in functional assays. SAR studies in the CCK region examined the structural requirements for the side chain groups at positions 1', 2', and 4' and for the N-terminal protecting group, which are related to interactions not only with CCK, but also with opioid receptors. Most peptide ligands that showed high binding affinities (0.1-10 nM) for both delta and mu opioid receptors generally showed lower binding affinities (micromolar range) at CCK-1 and CCK-2 receptors, but were potent CCK receptor antagonists in the GPI/LMMP assay (up to Ke = 6.5 nM). The results indicate that it is reasonable to design chimeric bifunctional peptide ligands for different G-protein coupled receptors in a single molecule.
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http://dx.doi.org/10.1021/jm050851nDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1614704PMC
March 2006

Novel design of bicyclic beta-turn dipeptides on solid-phase supports and synthesis of [3.3.0]-Bicyclo([2,3])-leu-enkephalin analogues.

Org Lett 2004 Sep;6(19):3285-8

Department of Chemistry, University of Arizona, 1306 East University Boulevard, Tucson, Arizona 85721, USA.

[structure: see text] External bicyclic beta-turn dipeptide mimetics provide an excellent design approach that can offer a rich chiral ensemble of structures with different backbone conformations. We report herein a novel design of a convergent combinatorial synthetic methodology, which is illustrated by the solid-phase synthesis of a series of [3.3.0]-bicyclo([2,3])-Leu-enkephalin analogues. The reactions were optimized and the epimeric configurations were determined by 2D NMR spectroscopy. Biological assays show that these analogues have more potent delta binding affinity and bioactivity for delta vs micro opioid receptor, which may be related to the different conformations preferred by these analogues in our modeling studies.
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http://dx.doi.org/10.1021/ol0488183DOI Listing
September 2004

Design of peptide agonists.

Methods Enzymol 2002 ;343:73-91

Department of Chemistry, University of Arizona, Tucson, Arizona 85721, USA.

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http://dx.doi.org/10.1016/s0076-6879(02)43128-xDOI Listing
February 2002