Berechnung des Circulardichroismus von beta-Oligopeptiden und Oligonucleotiden mit dem klassischen 'Dipole Interaction Model' und der quantenmechanischen Matrixmethode

The spectrum of Circulardichroimus (CD) is sensitively dependent on the structure of the chiral molecules. Up to now the structure cannot be directly determined from the spectrum, but with the help of a suitable theory the spectra can be calculated from assumed structures and the structures can be confirmed or excluded therewith. In this thesis the CD-spectra are calculated from beta-peptides and polynucleotides according to the classical 'Dipole Interaction Model' of Applequist and the quantum mechanical 'matrix method'.As beta-peptides a hexa- and a hepta-peptide are examined. The calculations which are done at first according to the Applequist model show, however, that the model is unsuitable for calculating CD-spectra of larger and more densely packed polypeptides. An analyses of the model shows that the polarizabilities which are assigned to the single atoms are responsible for this.Using the matrix method, the calculations which have to be done for the chromophoric groups of the molecule, are done according to the time dependent density functional theory (TDDFT). The calculations which are done for the beta-hexa- and beta-heptapeptides and different quadruplexes show a good agreement with the experiment. In the examination of the base-flipping mechanism of the DNA, in which Beuck and Weinhold have replaced a base with the appropriate thiobase at different positions of the DNA (Beuck, Promotion 2004, RWTH-Aachen), the theoretical spectra show qualitatively the same change with the flipped base as in the experimental spectra too.It is thereby confirmed that the matrix method together with the TDDFT calculations for the groups of the molecule is suitable for the examination of the structure of beta-peptides and oligonucleotides.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2006

Author dc:creator

• Repges, Rudolf

Contributors dc:contributor

• Fleischhauer, Jörg

• info:eu-repo/classification/ddc/540
• Chemie
• Zirkulardichroismus
• Matrixmethode
• Beta-Peptide
• Quadruplexe
• Basenausklappmechanismus
• matrix method
• beta-peptides
• quadruplexes
• base-flipping

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-122900%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:61222