Redox: Determine midpoint potential

[OldManMahoney]

I currently have a question sheet of biochemical statistics that I'm trying to work through. I would very much love any hints or examples of what to do for this question. I really don't know what to do, or where to begin!

The reduction of a ferredoxin with ditionite (under anaerobic conditions), gave the spectra 'a' to 'h' as shown in the figure below:

 

http://yfrog.com/0yimg28880j

 

 

Spectrum 'a' represents a fully oxidised state and 'h' shows a fully reduced state. Spectra b-g represent partially and increasingly reduced ferredoxin. The volume was constant throughout the experiment and the changes in absorbance at 460 nm were linear with regard to the state of reduction of the ferredoxin.

 

The potentials relative to a calomel electrode (+244 mV) when each spectrum was recorded is:

 

Spectrum A B C D E F G H

Potential (mv) -530 -588 -619 -635 -640 -670 -705 -740

 

Determine the midpoint of the protein and whether it transfers one or two electrons.

[paige anthony]

Did you ever find out how to do this, i have had a similar work sheet set.