DAT Destroyer Bio Question #14

[DesiDenty]

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Hey guys,

I was wondering if someone could explain this problem's answer to me. Why do you need reducing conditions to disrupt a protein with 2 alpha units and 2 beta units joined by a disulfide bond? The solution doesn't do a good job of explaining why reducing conditions must be used as opposed to oxidizing conditions. Thanks!

 

[UCB05]

A R-S-S-R disulfide bond has two less electrons than two unbonded R-SH ends. To break a disulfide bond you have to essentially reduce the molecule (likely by using a hydride ion H-), and so to do that would require reducing conditions. Oxidizing conditions won't help you break disulfide bonds.

 

[DesiDenty]

Oh ok, that makes sense. So would that mean if you're trying to join together two R-SH's together, you would need oxidizing conditions to get rid of the H's? Thanks for the quick reply!

 

[UCB05]

Yep, and/or an electron-acceptor to balance out the redox reaction

 

[ToZanarkand]

A R-S-S-R disulfide bond has two less electrons than two unbonded R-SH ends. To break a disulfide bond you have to essentially reduce the molecule (likely by using a hydride ion H-), and so to do that would require reducing conditions. Oxidizing conditions won't help you break disulfide bonds.

Good explanation. I also didn't know the reason. Thank you.🙂

 

[sfoksn]

You guys probably learned this concept in your molecular genetics course with lab, when you used SDS-PAGE gel electrophoresis to determine protein sizes 😀

 

[Ibracadabra]

That's why disulfide bonds most likely(or maybe always) form inside the lumen of the ER. The cytoplasm is an reducing environment, so cytosolic proteins don't have disulfide bonds.

Please correct me if I'm wrong.. but I believe I read this somewhere.