Up till now, there are two kinds of 2x Laemmli sample buffers:
Buffer 1) 65.8 mM Tris-HCl, pH 6.8, 2.1% SDS, 26.3% (w/v) glycerol, 0.01% bromophenol blue
Please refer to the original paper: Cleavage of structural proteins during the assembly of the head of bacteriophage T4
http://www.academia.edu/3313242/Cleavage_of_structural_proteins_during_the_assembly_of_the_head_of_bacteriophage_T4
And BioRad, Cat# 161-0737.
Buffer 2) 4% SDS, 20% glycerol, 10% 2-mercaptoethanol, 0.004% bromphenol blue and 0.125 M Tris HCl, pH approx. 6.8
Please refer to Sigma, Cat# S3401. And Cold Spring Harbor Protocols.
Buffer 1) is for optimal band resolution based on BioRad manual.
Does anybody know the advantage of buffer 2)?
Thanks.
http://www.bio-rad.com/en-mx/sku/161-0737-2x-laemmli-sample-buffer
http://www.sigmaaldrich.com/catalog/product/sigma/s3401?lang=en®ion=US