SDS-PAGE Loading Buffer with Ficoll? - (Oct/17/2007 )

I read that using a loading buffer with ficoll when running a polyacryamide gel for DNA and RNA will yield sharper bands. I was wondering if the same would be true for protein gels.
Has anyone tried this before? Also, has anyone used LDS (lithium dodecyl sulfate) instead of SDS in their loading buffer?

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Don't know about Ficoll, but LDS.. yes. Invitrogen's NuPAGE sample loading buffer has 2% LDS. They say that SDS generally precipitates at high concs while LDS is "much more soluble".

FYI this is LDS sample buffer:
Glycerol_10%, Tris Base_141 mM, Tris HCl_106 mM, LDS_2%, EDTA_0.51 mM, SERVA® Blue G250_0.22 mM, Phenol Red_0.175 mM, pH 8.5

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Ficoll prevents sample diffusion. Glycerol does the same. SDS-PAGE has a stacking gel which compress the sample into find band. Using Ficoll probably does not bring in major changes.

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This makes sense. The stacking gel will stack no mather what density increaser you use. But I still wonder if it is worth a shot. I was thinking of trying a 1X Ficoll concentration of 2.5%.
This will also allow the buffer to be stored at room temp w/o problems.

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Actually this is the sample buffer we are using right now. We buy it straight from Invitrogen. I am wondering if LDS is as strong denaturant as SDS is. I am also thinking of maybe adding some additional SDS to the sample buffer. I am worried about this because our protein is hard to denature.

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lds is purer (chain length) than sds so it is easier to determine molar concentration.

also, it won't crystallize at refrigerator temperatures so it can be used to run gels at cold temperatures without fear of microcrystal formation in the gel.

otherwise, it is as effective as sds in denaturing proteins. there is no need to supplement it with sds.

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I think ficoll is a type of sugar that will bind any nucleic acid and causes it to sink to the bottom of the solution.

I don't know about protein though but i think ficoll is only applicable to nucleic acids.

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