Molecular cloning -Sambrook et al/ Tris base vs TRIZMA

arturo.galvani at itner.pharmacia.se arturo.galvani at itner.pharmacia.se
Mon Jun 5 10:44:13 EST 1995


"T.S. Pillay" <tpillay at ucsd.edu> writes:
     
In the electrophoresis section in Molecular Cloning by Sambrook et al 
(a.k.a. the "Maniatis")  it says not to use TRIZMA for SDS PAGE 
electrophoresis buffers but Tris Base which should be pH'd to the 
appropriate pH instead of using a mixture of Trisbase and Tris-HCl.  Does 
anyone know the reason for this.
___________________________________________________________________________
     
     I don't have Maniatis at hand, so I can't comment directly on the 
     passage you mention, but I do remember hearing somewhere that tris 
     base should be used because when mixed with glycine in the right 
     proportion (192 mM glycine, 25 mM Tris), the pH jumps out right (8.3) 
     with no need to pH.  Using Tris-HCL at the same concentrations of Tris 
     and glycine introduces the need to pH with sodium hydroxide, thus 
     putting salt into the buffer. This makes the buffer more conductive, 
     and therefore would cause greater Joule heating. This can cause 
     particular problems in high current applications (i.e. when 
     transferring for westerns). 
     
     Leading on from this, if someone can explain to me why some pH 
     electrodes don't like Tris.......
     
     Arturo Galvani
     Pharmacia BioPharm, Milan Italy (usual disclaimer applies).
     
     "The English and the Americans are two peoples divided by a common 
     language"
     - Oscar Wilde.




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