SDS PAGE Prerunning Before Loading Sample

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annivsahra_p's picture
SDS PAGE Prerunning Before Loading Sample

Hello sir. mam,

Well in advance i thank you very much .. i have some doubt regarding SDS page.. after pouring the tank buffer shall we run the gel without loading sample. then turn of the power pack and loading the sample and then we run the process.. it makes any usefulness to us.. or else it makes some problem to the proteins or to gel.

What pH should be maintain in the upper part of the tank buffer and lower part of the tank buffer.. if we change any pH alteration in the both buffer will rise any problem ....

i hope your golden comments...

qiang wang
qiang wang's picture
sorry for the late answer,

sorry for the late answer, hopefully you are still with us at

the link below by Dr. Dyche Mullins at UCSF has an excellent explanation on how SDS-PAGE works.

for your fist question, no, you do not prerun an SDS-gel.

and for your second question, we usually run SDS-PAGE with pH6.8 for stacking gel and pH8.3 for resolving gel.

third, you may adjust the pH only when you are a master of SDS-PAGE, and you know what you are doing.

Shubhangi's picture

sometimes pre running a gel is advisible as it gives good resolution of bands and avoids spread or smiling gels.

Jason King
Jason King's picture
Pre-running an acrylamide gel

Pre-running an acrylamide gel to get the temperature up and reduce the smiling front was only used for DNA sequencing gels.
Does anyone else remember the fun involved in pouring a long, extra thin sequencing gel? Character-building stuff!

g a
g a's picture
Pre running SDS PAGE gels....

Pre running SDS PAGE gels..... is not recommended for the discontinuous gels where you have a stacking gel towards pH 6.8 and then a resolving gel with pH 8.8 or more.....
pre run in that case removes the discontinous migartion of protein ions and hence the entire logic of running a discontinuous gel is vanished.
However, for continuous gels you can pre run the gels if you are going to proceed for the Mass spectrometry. you pre run yr gels and then decant the buffers and again repour the fresh running buffer and perform SDS PAGE.
This prevents the keratin contamionation in the gels..