Can SDS-PAGE detect monomer and polymer?
If it can, DTT should be added prior to load in gel?
Dear Liming
it depends from the stability and the nature of the polimer.
For example:
In vitro pilus polimerization mediated my sortases involve the formation of stable covalent bonds0( stable also in presence of DTT) you can detect it in standard SDS page with presence of DTT.
On the contrary, if polimerization if mediated by S-S bond formation, as for example happen in full lenght antibodies (with DTT you see the saparate chains with-Out DTT you see the full lenght antibody) or the SOD1 fibrils, you can see the polimer only in absence of DTT.
In some cases (eg dimer Cu,ZN SOD1 form ) you can see the mature dimer also avoiding sample boiling.
There is not a common rule, the result depends from the nature and the strenght of the interactions that promote the protein polmerization.
I think that to solve your doubts , you have just to try the different conditions as
no boiling, no DTT,
boiling, no DTT
boiling + DTT
and compare the results.
If you think that your polimer will be characterized form very high molecular weight, you have to use 3-7/ tris-acetate gels because with standard gel you will be not able to resolve MW>200KDa
good luck
Manuele
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