which gel concentration can separate the 7.5 kDa protein? - (Nov/18/2011 )

which gel concentration can separate the 7.5 kDa protein?

Have a look for Roche Lab FAQs, in the section on proteins, there is a diagram for this sort of thing.

For denatured protein of 7.5KDa try using 15% or 12% SDS-PAGE gels

12% wont get the resolution you want.
I'd go 15% gels, run them all the time to get 13, and 16kda proteins.

10% tris-tricine sds page should be good for 7.5 kDa.

I tried using 12% and 15% SDS-PAGE gels, but it didn't work. I will try using 10% tris-tricine SDS-PAGE. Are there anything different between sample buffer used for glycine SDS-PAGE and tricine SDS-PAGE?

i use the same sample buffer for both.