THE ANGULAR DEPENDENCE OF NUCLEAR SPIN-SPIN COUPLING CONSTANTS IN COMPOUNDS WHICH MODEL THE PEPTIDE BACKBONE (POLYPEPTIDES, LACTAMS).

Persistent Link:
http://hdl.handle.net/10150/187599
Title:
THE ANGULAR DEPENDENCE OF NUCLEAR SPIN-SPIN COUPLING CONSTANTS IN COMPOUNDS WHICH MODEL THE PEPTIDE BACKBONE (POLYPEPTIDES, LACTAMS).
Author:
KAO, LUNG-FA.
Issue Date:
1983
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:
Because polypeptides present a repeating sequence of amide bonds, lactams provide good model compounds for investigating the angular dependencies of coupling constants over a range of rigid conformations. A number of ¹³C labeled lactams were synthesized to cover a range of dihedral angles; experimental and theoretical carbon-carbon and carbon-hydrogen coupling constants were obtained to give the relationships between the vicinal coupling constants ³J[C(O)-N-C-C], ³J[C(O)-N-C-H] and dihedral angle φ. Vicinal ¹³C-¹³C coupling constants for dihedral angles in the range of 90° to 180° were obtained unambiguously from the coupling between the carbonyl and carbons in the side chains of lactams. However, due to coupling via multiple paths, vicinal ¹³C-¹³C coupling constants for dihedral angles ranging from 0° to 90° were estimated by excluding the contributions from the geminal ²J[C(O)-C-C] or vicinal ³J[C(O)-C-C-C] couplings in the lactam rings. The experimental and theoretical results show that the angular dependence of vicinal ¹³C-¹³C coupling constants do not follow a simple Karplus type relationship, especially at small dihedral angles. It was found that geminal ²J[C(O)-N-C] were small ( < 0.3 Hz). However, the ²J[C(O)-N-C] in the cis arrangement are shifted to about 2.2 Hz in N-methyl substituted lactams while in the trans arrangement the values are about 4.4 Hz. Geminal ¹³C-¹³C coupling constants ²J[(C(O)-N-C)] also provide a useful tool in stereochemical studies.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Coupling constants.; Peptides.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Chemistry; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Barfield, Michael

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleTHE ANGULAR DEPENDENCE OF NUCLEAR SPIN-SPIN COUPLING CONSTANTS IN COMPOUNDS WHICH MODEL THE PEPTIDE BACKBONE (POLYPEPTIDES, LACTAMS).en_US
dc.creatorKAO, LUNG-FA.en_US
dc.contributor.authorKAO, LUNG-FA.en_US
dc.date.issued1983en_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.abstractBecause polypeptides present a repeating sequence of amide bonds, lactams provide good model compounds for investigating the angular dependencies of coupling constants over a range of rigid conformations. A number of ¹³C labeled lactams were synthesized to cover a range of dihedral angles; experimental and theoretical carbon-carbon and carbon-hydrogen coupling constants were obtained to give the relationships between the vicinal coupling constants ³J[C(O)-N-C-C], ³J[C(O)-N-C-H] and dihedral angle φ. Vicinal ¹³C-¹³C coupling constants for dihedral angles in the range of 90° to 180° were obtained unambiguously from the coupling between the carbonyl and carbons in the side chains of lactams. However, due to coupling via multiple paths, vicinal ¹³C-¹³C coupling constants for dihedral angles ranging from 0° to 90° were estimated by excluding the contributions from the geminal ²J[C(O)-C-C] or vicinal ³J[C(O)-C-C-C] couplings in the lactam rings. The experimental and theoretical results show that the angular dependence of vicinal ¹³C-¹³C coupling constants do not follow a simple Karplus type relationship, especially at small dihedral angles. It was found that geminal ²J[C(O)-N-C] were small ( < 0.3 Hz). However, the ²J[C(O)-N-C] in the cis arrangement are shifted to about 2.2 Hz in N-methyl substituted lactams while in the trans arrangement the values are about 4.4 Hz. Geminal ¹³C-¹³C coupling constants ²J[(C(O)-N-C)] also provide a useful tool in stereochemical studies.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectCoupling constants.en_US
dc.subjectPeptides.en_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.advisorBarfield, Michaelen_US
dc.identifier.proquest8404669en_US
dc.identifier.oclc690638733en_US
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