APS & TEMED in acid gels

Sonya Clark saclark at nature.Berkeley.EDU
Mon Jan 27 14:38:45 EST 1997

I found using riboflavin is extremely useful for acid gels as the
APS/TEMED combination don't work well in acid conditions.  Riboflavin acts
to accelerate polymerization.  

To quote from Hames G., and Rickwood, D. Gel electrophoresis of proteins A
practical approach. 1990. - " In the APS-TEMED system TEMED catalyses the
formation of free radicals from persulphate and these in turn initiate
polymerisation.  Since the free base of TEMED is required, polymerization
may be delayed or even prevented at low pH.  increases in either the TEMED
or APS concentration increase the rate of polymerization.  In contrast
.... the use of riboflavin/TEMED requires light to initiate polmerization. 
This causes photodecomposition of riboflavin and production of the
necessary free radicals.  Although gelation occurs when solutions
containing only acrylamide and riboflavin are irradiated, TEMED is usually
also included since under cetain conditions polymerization occurs more
reliably in its presence." 

Stock solution: 4 mg riboflavin in 100 ml of water. Store at 4oC in dark.

I add half as much vol of this stock as I use of TEMED in stacking gels
for SDS-PAGE to get guaranteed perfect wells.  Sorry, can't find how much
exactly you use for acid gels - I think it might be about the same ratio.. 
I have that info at home and will look it up if someone asks me! Ciao

Sonya Clark
Albany CA
saclark at nature.berkeley.edu

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