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low MW bands left on gel during transfer to PVDF - (Jan/22/2007 )

Hi,
My problem is transfering protein bands less than 30 KDa to PVDF membranes. I used 4-20% Tris-HCl gels for SDS-PAGE running at 150V for 1 hr 30 min and using 25 mM Tris, 192 mM Glycine, 0.1% SDS pH 8.3 as running buffer. I then equilibrate my gels as well as PVDF membranes prewetted in methanol for ~2-3 seconds in pre-chilled transfer buffer - 25 mM Tris, 192 mM Glycine, 20% Methanol, 0.05% SDS pH 8.3 at room temperature for 30 minutes. I use the BioRad transblot system, set up the cassettes submerged in transfer buffer. I transfer at 20V at 16C overnight. Although all my molecular weight marker bands transfer to the membranes, after staining the gels, I find that some of the lower MW bands do not transfer. Interestingly, this problem cropped up only recently. I would really appretiate if someone has any suggestions. Am I using too much methanol or too less SDS or are my fiber pads getting old?
Thanks in advance,
jaylab.

-jaylab-

If this protocol of yours worked before and its not working now, try to make up new buffers and try it again.

We use 10% methanol and not use sds in our transfer buffer (This is what we use).

-scolix-