pH vs. Temperature for Tris - What will be the pH if you boil Lämmli (25mM Tris, pH 8,0)?? (Aug/15/2007 )

Hi,

Today, a colleague mentioned that it's probably not such a good idea to boil protein samples for SDS-PAGE in standard lämmli buffer, which contains 25mM Tris, pH 8,0 as buffering system, simply because for tris the pH will shift to very low values at 100°C, which could lead to hydrolysis of proteins, if you're REALLY unlucky. He recommended Na-phosphate or similar.
I looked it up on google and found some tables about pH vs. temperature in Tris in the range of 5-37°C, but nothing for 100°C. In case somebody is interested, there is a paper about various buffers and their pH vaues at different temperatures (not for tris, though).

I'm aware that this question is purely academic . But still I find it interesting... Does anybody know at which pH you end up when you boil Tris? An educated guess is appreciated as well .

Thanks!
dedee

The dye bp blue is pH sensitive, which turns yellow when pH is acidic. You did not see that happen during heating, right?