[Med lab student]

Hi,

We did an experiment in college where we used ion exchange chromatography to separate a mixture of cytochrome c and katalase. The experiment was succesful, we could clearly see the 2 separate components afterwords. But we had to do a test to make sure it was cytochrome c in 1 test tube and katalase in the other. For the cytochrome c, we added a little Na₂S₂O₄, and the color turned bright pink, so the test was positive. We are supposed to explain what caused the change in color, and I just can't figure it out. Is there anybody who can help me?
Thanks a lot in advance.

[chenbeier]

What kind of chemical is dithionite?

[Med lab student]

sodium dithionite , aka sodium hydrosulfite (Na₂S₂O₄)

[chenbeier]

No I mean what behaviour has this compound.

[Babcock_Hall]

According to the rules of the forum, you must provide your thoughts before we can help you.  What is the prosthetic group in cytochrome c?  What is the biochemical function of cytochrome c?

[Med lab student]

I understand. Cytochrome c has a heme prosthetic group, so it's a hemoprotein. Meaning it has the same red pigment as hemoglobin. Its function is involvement in the electron transport system in oxidative phosphorilation. I don't really get how that has to do with the reaction in question though. I'm sorry, I didn't take biochemistry yet, so I don't know that much about it.

[wildfyr]

There is a specific atom at the center of that heme, what might happen to it in the presence of sodium dithionite?

Sodium dithionite is a well known reagent of a certain class of chemicals. What is its main reactive pathway?Wikipedia should give it do you readily.

[Babcock_Hall]

Cytochrome c carries electrons from Complex III to Complex IV in the electron transport chain.  Carrying electrons is the job of the heme group, specifically the atom at the center of the heme group.