I never see the 16kDa band from the seeblue marker? - (Jan/09/2014 )
I use SeeBlue® Pre-Stained Standard from life technologies in SDS PAGE (12%). I never see the 16kDa band. Does anyone know why? Thanks!!
That's because it doesn't have one - it has 14 (lysozyme) and 18 (myosin) kDa bands. Seeblue plus2 has 14 and 17 kDa bands.
12% gels also won't properly resolve bands below about 20-25 kDa, so anything below this will either migrate out of the gel or diffuse quickly once the current is switched off.
Thanks bob1. I use tris-glycine runing buffer. and according this website :http://www.lifetechnologies.com/us/en/home/references/protocols/proteins-expression-isolation-and-analysis/sds-page-protocol/pre-stained-protein-standards-seeblue-plus2-protein-standard.html
the Lysozyme represent 16kDa. I can see the one above it, the red one (Myoglobin) and two bands below the Myoglobin, but according there position, they should be Aprotinin and insulin B chain, because they are quite far away from the red one.
I still don't understand why the one right below the red Myoglobin is missing.
Huh, I looked them up and didn't find that page before, the pages I found showed different sizes.
The most likely scenario is that you are actually mis-identifying the bands below the red one. The pictures they show for these markers are always on acrylamide percentage gradient gels, so bands of similar sizes are closer than they would appear on a gel that isn't gradient based. On a 12% gel proteins of 6 kDa and 4 kDa will not be resolved properly and will run as one band.