Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Chemistry and Biochemistry

Committee Chair(s)

Thomas M. Farley (Committee Chair)


Thomas M. Farley


Jon Y. Takemoto


The purpose of this study was to identify the site of interaction of antimycin with the ubiquinone-cytochrome b-c1 oxidoreductase in the photosynthetic bacteria, Rhodopseudomonas sphaeroides. To accomplish this goal, three areas of research were undertaken: the synthesis of a radiolabeled, photoaffinity analog of antimycin, identification of the inhibitory characteristics of this analog, and the photoaffinity labeling of the antimycin binding site. All three areas were accomplished.

The major finding of this study was the identification of an 11,000 dalton polypeptide as the predominantly labeled protein. Although this polypeptide was not exclusively labeled, it was consistently labeled and showed competition with antimycin. These results are consistent with a similar study performed by das Gupta and Rieske (1973) with a mitochondrial preparation.

These results are not conclusive, but do show several interesting points. First, cytochrome b is not the only site of interaction of antimycin with the ubiquinone~cytochrome b-c1 region of the electron transport chain. Secondly, an 11,000 dalton polypeptide is an important component of this protein complex. The function of this polypeptide is unknown, but should provide interesting research for future studies.