Skip to main content
ARS Home » Research » Publications at this Location » Publication #95529
Title: EXTINCTION COEFFICIENTS AND MIDPOINT POTENTIALS OF CYTOCHROME C6 FROM SYNECHOCYSTIS 6803, MYCROCYTSTIS AERUGINOSA AND ARTHROSPIRA

Author
item CHO, Y. - PLANT BIOLOGY UOFI URBANA
item WANG, Q. - PLANT BIOLOGY UOFI URBANA
item KROGMANN, D. - PRUDUE UNIVERSITY INDIANA
item WHITMARSH, CLIFFORD

Submitted to: Biochimica et Biophysica Acta
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/14/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Photosynthetic electron transport provides the energy for the reduction of carbon dioxide and is responsible for the release of molecular oxygen into the atmosphere. We are investigating the proteins involved in electron transport in order to identify factors that control photosynthetic efficiency. The work described here focuses on a soluble heme protein, cytochrome c6, which serves to transfer electrons between large membrane bound protein complexes. The synthesis of this protein is controlled by the copper concentration of the growth medium. The long range goal is to use molecular genetics to identify structural features of the proteins that control electron transport and to understand how metal ions control gene expression. Here we describe the physical properties of the protein that partially control its electron transport activity. This work contributes to the basic knowledge needed to understand electron transport and its role in energy conversion.

Technical Abstract: Cytochrome c6 is a water soluble heme protein that carries electrons from the cytochrome bf complex to photosystem I in cyanobacteria. Understanding its role in photosynthetic electron transfer requires knowledge of its physical and thermodynamic properties. To this end we have isolated cytochrome c6 from three the cyanobacterium, Synechocystis 6803, Mycrocystis aeruginosa, Arthrospira sp., and determined its extinction coefficient and midpoint potential. The reduced minus oxidized extinction coefficients were determined by pyridine extraction of the heme and the midpoint potentials were determined by potentiometric titration.