Chemistry ETDs

Publication Date

Summer 7-21-1977


It was desired to help establish whether or not the tertiary structure of a biomolecule is the same in a cry­stal (or an oriented film) as it is in solution. Generally it is accepted that the structures in these diverse environ­ments are similar, if not identical. By comparing the extinction coefficients obtained from oriented film data to those obtained from solution data it was hoped that this question might further be resolved. To this end an electric dichroism instrument built in our lab was used to measure the dichroic signal so as to calculate, with the help of the ultraviolet absorption spectra of the solution, extinction coefficients in the parallel and perpendicular directions. These were then compared to data from the oriented film to determine whether the two sets of data could be rotated into each other using a computer program based on a linear programming method.

For the four nucleic acids studied, the two sets of data were found to be equivalent and required rotation through an angle of zero degrees to force this equivalence. It was also found that flow dichroism data and electric dichroism data were equivalent. It was thus established that the dipole moment is along the helical axis in the nucleic acids. Additionally it was shown that the physical, hydrodynamical, and electrical axes are symmetrical and coincident.

Decay curves for relaxation from the transient orienting phenomena were plotted and rotary diffusion coefficients were calculated using the peeling method for a two component system to yield both a slow and a fast relaxing component. Relaxation times were also calculated. And finally it was observed that the elec­tric dichroism instrument functioned correctly in that it could reproduce literature values.

Document Type


Degree Name


Level of Degree


Department Name

Department of Chemistry and Chemical Biology

First Committee Member (Chair)

Fritz Schreyer Allen

Second Committee Member

David Lee Vander Jagt

Third Committee Member

William Fletcher Coleman