Glycopeptide and Phosphopeptide Analogs of DAMGO: A Study on the Role of Amphipathicity to Promote Blood Brain Barrier Penetration

Persistent Link:
http://hdl.handle.net/10150/195248
Title:
Glycopeptide and Phosphopeptide Analogs of DAMGO: A Study on the Role of Amphipathicity to Promote Blood Brain Barrier Penetration
Author:
Yeomans-Maldonado, Larisa
Issue Date:
2009
Publisher:
The University of Arizona.
Rights:
Copyright © 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.
Abstract:
Glycosylation may be a general strategy for the transport of biologically active neuro(glyco)peptides into the brain. With that in mind, a series of modified DAMGO analogues were synthesized and subjected to conformational analysis, and in vitro and in vivo studies related to opioid analgesia. Those studies will help to determine the balance of carbohydrate and peptide, to reach maximum BBB transport; in other words this is a study to test the biousian hypothesis. 1) The μ-agonist DAMGO was altered by incorporating moieties of increasing water solubility into the C-terminus, including carboxamide and simple glycosides. The hydrophilic C-terminal moieties were varied from glycinol in DAMGO to L-serine amide (LYM100), L-serine amide β-D-xyloside (LYM50), L-serine amide β-Dglucoside (LYM110), L-serine amide β-lactoside (LYM147). Two phosphopeptides LYM1311 and LYM1312 were synthesized with the phosphate group attached to Lserine amide at the C-terminus. Conformational analysis experiments included: 1HNMR, diffusion, variable temperature experiments to find the temperature coefficient, circular dichroism, 2DNMR noesy and tocsy, and molecular modeling. The peptides associate with SDS micelles with a strong electrostatic component. The SDS micelles stabilized the β-turn that is nascent in water. CSI (chemical shift indexes), temperature coefficients and circular dichroism do not give much insight into the structural conformation. 2D NMR analysis followed by molecular modeling confirmed a β-turn preferred conformation. No specific type of β-turn could be assigned to the DAMGO analogs. 2) Antinociceptive mouse tail-flick studies were performed, and opioid binding was determined. Analgesic potency (i.v.) increased, passing through a maximum (A₅₀ ≈ 0.2 μmol/Kg) for LYM100 & LYM50 as membrane affinity vs. water solubility became optimal, and then dropped off (A₅₀ ≈ 1.0 μmol/Kg) for LYM110 & LYM147 as water-solubility dominated the molecular behavior. Correlation of i.v. A₅₀ values with estimated hydrodynamic values (glucose units) for the glycoside moieties, or the hydrophilic/hydrophobic Connolly surface areas (A₅₀ vs e^(-Awater/Alipid)), provided U-shaped or V-shaped curves, as predicted by the “biousian hypothesis.” The μ-selective opioid agonism was maintained upon modifications at the C-terminus. The optimal “degree of glycosylation” that achieves the maximum degree of transport for the DAMGO peptide message seems to be between the peptide with the carboxamide C-terminal group and the xyloside.
Type:
text; Electronic Dissertation
Keywords:
amphipatic; bbb; Blood brain barrier; glycopeptide; NMR; phosphopeptide
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Chemistry; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Polt, Robin L.
Committee Chair:
Polt, Robin L.

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleGlycopeptide and Phosphopeptide Analogs of DAMGO: A Study on the Role of Amphipathicity to Promote Blood Brain Barrier Penetrationen_US
dc.creatorYeomans-Maldonado, Larisaen_US
dc.contributor.authorYeomans-Maldonado, Larisaen_US
dc.date.issued2009en_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.description.abstractGlycosylation may be a general strategy for the transport of biologically active neuro(glyco)peptides into the brain. With that in mind, a series of modified DAMGO analogues were synthesized and subjected to conformational analysis, and in vitro and in vivo studies related to opioid analgesia. Those studies will help to determine the balance of carbohydrate and peptide, to reach maximum BBB transport; in other words this is a study to test the biousian hypothesis. 1) The μ-agonist DAMGO was altered by incorporating moieties of increasing water solubility into the C-terminus, including carboxamide and simple glycosides. The hydrophilic C-terminal moieties were varied from glycinol in DAMGO to L-serine amide (LYM100), L-serine amide β-D-xyloside (LYM50), L-serine amide β-Dglucoside (LYM110), L-serine amide β-lactoside (LYM147). Two phosphopeptides LYM1311 and LYM1312 were synthesized with the phosphate group attached to Lserine amide at the C-terminus. Conformational analysis experiments included: 1HNMR, diffusion, variable temperature experiments to find the temperature coefficient, circular dichroism, 2DNMR noesy and tocsy, and molecular modeling. The peptides associate with SDS micelles with a strong electrostatic component. The SDS micelles stabilized the β-turn that is nascent in water. CSI (chemical shift indexes), temperature coefficients and circular dichroism do not give much insight into the structural conformation. 2D NMR analysis followed by molecular modeling confirmed a β-turn preferred conformation. No specific type of β-turn could be assigned to the DAMGO analogs. 2) Antinociceptive mouse tail-flick studies were performed, and opioid binding was determined. Analgesic potency (i.v.) increased, passing through a maximum (A₅₀ ≈ 0.2 μmol/Kg) for LYM100 & LYM50 as membrane affinity vs. water solubility became optimal, and then dropped off (A₅₀ ≈ 1.0 μmol/Kg) for LYM110 & LYM147 as water-solubility dominated the molecular behavior. Correlation of i.v. A₅₀ values with estimated hydrodynamic values (glucose units) for the glycoside moieties, or the hydrophilic/hydrophobic Connolly surface areas (A₅₀ vs e^(-Awater/Alipid)), provided U-shaped or V-shaped curves, as predicted by the “biousian hypothesis.” The μ-selective opioid agonism was maintained upon modifications at the C-terminus. The optimal “degree of glycosylation” that achieves the maximum degree of transport for the DAMGO peptide message seems to be between the peptide with the carboxamide C-terminal group and the xyloside.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectamphipaticen_US
dc.subjectbbben_US
dc.subjectBlood brain barrieren_US
dc.subjectglycopeptideen_US
dc.subjectNMRen_US
dc.subjectphosphopeptideen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineChemistryen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorPolt, Robin L.en_US
dc.contributor.chairPolt, Robin L.en_US
dc.contributor.committeememberHruby, Victoren_US
dc.contributor.committeememberMash, Eugeneen_US
dc.contributor.committeememberBrown, Michaelen_US
dc.contributor.committeememberWysocki, Vickien_US
dc.identifier.proquest10769en_US
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