strange band in coomassie blue staining - (Jan/16/2010 )

Hi everyone,

Yesterday i stained my SDS-PAGE gel using coomassie blue, i find there is a band about 70kDa in every lane including sds loading dye lane without sample.

Does it show my sds loading dye is contaminated? i always use the same loading dye. or sds loading dye can be stained by coomassie blue?

Does anyone have this experience, please tell me

Hi,
What is your sample and how did u prepare it? A purified protein or cell lysate or...? 70kDa protein is likely to be a heat shock protein which might sometimes come along with the protein of interest being purified from bacteria. however if u see it even without sample, then the best explanation would be the one u did as far as I can imagine. I would simply take a fresh loading dye, which u r sure is not contaminated and see whether u still see this protein or not. U should not see it in the lane without sample since comassie only binds to proteins and nothing else that is present in loading dye. U might still see this protein in your sample lanes since it might be a common bacterial heat shock protein, which definitely comes along with Nickel beads. Keep me updated please.

Cheers,
Volkan

1324409 on Jan 16 2010, 03:45 PM said:

you may be seeing an artifact that appears as the reducing agent ages. it is from keratins in dust. (i feel like a broken record)