Does SDS PAGE break up protein polymers under nonreducing conditions?

[BlueComet]

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I thought it didnt but from the section bank, in one problem they seem to think that it does. Does anyone know for sure?

 

[BlueComet]

 

[chaim123]

I thought it didnt but from the section bank, in one problem they seem to think that it does. Does anyone know for sure?

SDS will break up protein polymers unless they are held together by disulfide bonds - those bonds require reducing conditions to be broken.

 

[BlueComet]

Thank you!!

 

[esob]

Unless you are taking a NS exam, at which point they expect you to assume (incorrectly) that SDS is always performed under reducing conditions.

 

[timephone]

So just to clarify (b/c I have nothing better to do), there are three types of gel experiments that are run with proteins:
(PAGE = Poly-Acrylamide Gel Electrophoresis)

--Native PAGE
--SDS-PAGE
--Reducing-PAGE

Native PAGE:
Least common gel electrophoresis. Protein is run through gel in its "native state", i.e. as a big globular ball.
***Tertiary and quaternary structures remain intact

SDS-PAGE
Uses SDS (sodium dodecylsulfate) as a detergent to disrupt hydrogen bonds and hydrophobic interactions that keep protein in native shape.
***Disrupts tertiary and quaternary structure not linked by disulfide bonds

Reducing-SDS-PAGE
Uses beta-mercaptoethanol (most commonly, sometimes other reducing agents are used) to break disulfide bonds.
***Tertiary and quaternary structure is completely dismantled, only secondary structures remain

 

[timephone]

View attachment 234114

The homotrimers will break up under normal (non-reducing) SDS-PAGE because the three identical subunits must be linked with either one or a combination of hydrogen bonds, hydrophobic surface interactions, and/or salt bridges. The SDS detergent will disrupt these interactions and result in three separate unassociated peptide chains.

 

[BlueComet]

The homotrimers will break up under normal (non-reducing) SDS-PAGE because the three identical subunits must be linked with either one or a combination of hydrogen bonds, hydrophobic surface interactions, and/or salt bridges. The SDS detergent will disrupt these interactions and result in three separate unassociated peptide chains.

Thank you! I feel I have a very good understanding now and wont get this question wrong on my saturday MCAT.

Thanks again!

 

[Oso]

Did I learn/know this information at some point in my life?!?

 

[Lucca]

Moving to study questions