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dc.contributor.advisorHruby, Victor J.en_US
dc.contributor.authorLiao, Subo, 1963-
dc.creatorLiao, Subo, 1963-en_US
dc.date.accessioned2013-04-18T09:45:55Z
dc.date.available2013-04-18T09:45:55Z
dc.date.issued1997en_US
dc.identifier.urihttp://hdl.handle.net/10150/282418
dc.description.abstractTopographical constraint is the most powerful approach for the design of bioactive peptides to explore the bioactive conformation of crucial side-chain pharmacophores of amino acid residues in peptide-receptor recognition and signal transduction. Novel topographically constrained amino acids β-isopropylphenylalanine and 2',6'-dimethyl-2,3-methanophenylalanine have been designed and synthesized. Incorporation of the four optically pure β-isopropylphenylalanine stereoisomers into deltorphin I produced four peptide analogues of [β-iPrPhe]Deltorphin I with differentiated bioactivities. The most potent and selective analogue, [(2S,3R)-β-iPrPhe]Deltorphin I showed an IC₅₀ nM binding affinity, and a 29000 fold selectivity for the δ-opioid receptor over the μ opioid receptor. Combined molecular modeling and NMR studies indicated that the (2S,3R)-β-iPrPhe³ residue in the analogue favors the trans rotamer, and can induce the linear peptide to form a low-energy folded conformation which was proposed as the bioactive conformation for the δ-opioid receptor. Coupling four optically pure, conformationally constrained β-methyl-2',6'-dimethyltyrosine (TMT) with L-Tic formed four dipeptide analogues of TMT-L-Tic. The most potent and selective analogue, (2S,3R)-TMT-L-Tic showed 9 nM binding affinity and 4000 fold selectivity to the δ vs μ opioid receptor. The lowest-energy conformation of (2S,3R)-TMT-L-Tic was suggested to be the bioactive one in which TMT side chain is trans and Tic side chain is in a gauche (+) conformation. Bicyclic oxytocin antagonist [dPen¹, cyclo(Glu⁴ Lys⁸)]OT (BC-OT) (pA₂ = 8.10) is an excellent template to examine further topographical ideas. Substitution of Tyr² with the topographically constrained para-methoxy-β-methyl-2',6'-dimethyltyrosine (p-MeOTMT) amino acids produced two very potent antagonists [(2S,3S)-p-MeOTMT²]BC-OT (pA₂ = 8.26) and [(2R,3R)-p-MeOTMT²]BC-OT(pA₂ = 7.80), and two inactive analogues [(2S,3R)-p-MeOTMT²]BC-OT and [(2R,3S)-p-MeOTMT²]BC-OT. These interesting results can be attributed to the biased side-chain conformation, gauche(+) and gauche(-) in (2S,3S)-p-MeOTMT and (2R,3R)-p-MeOTMT respectively, and trans in both (2S,3R)-p-MeOTMT and (2R,3S)-p-MeOTMT residues. Rational design of non-peptide mimetics from peptide leads is still elusive. Based on the δ-opioid selective lead [(2S,3R)-TMT¹]DPDPE and SAR of δ-opioid selective ligands, the first generation of non-peptide mimetics have been designed and synthesized. The new lead SL-3111 showed binding affinity IC₅₀ = 8 nM, and over 2000 fold selectivity for the δ-opioid receptor over the μ receptor.
dc.language.isoen_USen_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.subjectChemistry, Organic.en_US
dc.subjectChemistry, Pharmaceutical.en_US
dc.titleDesign and synthesis of topographically constrained amino acids, and bioactive peptides for studies of ligand-receptor interaction, and for de novo design of delta-opioid selective non-peptide mimetics as potential therapeuticsen_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
thesis.degree.grantorUniversity of Arizonaen_US
thesis.degree.leveldoctoralen_US
dc.identifier.proquest9806802en_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineChemistryen_US
thesis.degree.namePh.D.en_US
dc.identifier.bibrecord.b37541390en_US
refterms.dateFOA2018-09-05T17:53:02Z
html.description.abstractTopographical constraint is the most powerful approach for the design of bioactive peptides to explore the bioactive conformation of crucial side-chain pharmacophores of amino acid residues in peptide-receptor recognition and signal transduction. Novel topographically constrained amino acids β-isopropylphenylalanine and 2',6'-dimethyl-2,3-methanophenylalanine have been designed and synthesized. Incorporation of the four optically pure β-isopropylphenylalanine stereoisomers into deltorphin I produced four peptide analogues of [β-iPrPhe]Deltorphin I with differentiated bioactivities. The most potent and selective analogue, [(2S,3R)-β-iPrPhe]Deltorphin I showed an IC₅₀ nM binding affinity, and a 29000 fold selectivity for the δ-opioid receptor over the μ opioid receptor. Combined molecular modeling and NMR studies indicated that the (2S,3R)-β-iPrPhe³ residue in the analogue favors the trans rotamer, and can induce the linear peptide to form a low-energy folded conformation which was proposed as the bioactive conformation for the δ-opioid receptor. Coupling four optically pure, conformationally constrained β-methyl-2',6'-dimethyltyrosine (TMT) with L-Tic formed four dipeptide analogues of TMT-L-Tic. The most potent and selective analogue, (2S,3R)-TMT-L-Tic showed 9 nM binding affinity and 4000 fold selectivity to the δ vs μ opioid receptor. The lowest-energy conformation of (2S,3R)-TMT-L-Tic was suggested to be the bioactive one in which TMT side chain is trans and Tic side chain is in a gauche (+) conformation. Bicyclic oxytocin antagonist [dPen¹, cyclo(Glu⁴ Lys⁸)]OT (BC-OT) (pA₂ = 8.10) is an excellent template to examine further topographical ideas. Substitution of Tyr² with the topographically constrained para-methoxy-β-methyl-2',6'-dimethyltyrosine (p-MeOTMT) amino acids produced two very potent antagonists [(2S,3S)-p-MeOTMT²]BC-OT (pA₂ = 8.26) and [(2R,3R)-p-MeOTMT²]BC-OT(pA₂ = 7.80), and two inactive analogues [(2S,3R)-p-MeOTMT²]BC-OT and [(2R,3S)-p-MeOTMT²]BC-OT. These interesting results can be attributed to the biased side-chain conformation, gauche(+) and gauche(-) in (2S,3S)-p-MeOTMT and (2R,3R)-p-MeOTMT respectively, and trans in both (2S,3R)-p-MeOTMT and (2R,3S)-p-MeOTMT residues. Rational design of non-peptide mimetics from peptide leads is still elusive. Based on the δ-opioid selective lead [(2S,3R)-TMT¹]DPDPE and SAR of δ-opioid selective ligands, the first generation of non-peptide mimetics have been designed and synthesized. The new lead SL-3111 showed binding affinity IC₅₀ = 8 nM, and over 2000 fold selectivity for the δ-opioid receptor over the μ receptor.


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