4 replies to this topic

[NattyB]

Hi all,
I am always making a buffer containing 10mM phosphate, 5mM DTT and 2mM EDTA, and i was just wondering how long DTT is stable for at that concentration at 4deg to see if I could make enough to last a few weeks

[tfitzwater]

DTT is less stable in aqueous solutions.  According to Maniatis, dissolving DTT in 0.5 mM Na2EDTA will increase the stability.  
DTT has an absorbance peak of 220 nm, while the oxidized form has a peak at 300 nm.

Edited by tfitzwater, 10 November 2010 - 07:22 AM.

[rhombus]

NattyB, on 09 November 2010 - 11:13 AM, said:

Hi all,
I am always making a buffer containing 10mM phosphate, 5mM DTT and 2mM EDTA, and i was just wondering how long DTT is stable for at that concentration at 4deg to see if I could make enough to last a few weeks

Dear NattyB,

I always make up DTT fresh and never keep a stock solution...because it is so unstable.

Kindest regards

Uncle Rhombus

[tfitzwater]

50 mM buffer pH value 2 mM DTT is 50% oxidized
Tris®-HCl 7.6 22 hours
Tris®-HCl 8.0 5 hours
Tris®-HCl 8.5 2.5 hours
Tris®-HCl 9.0 1.5 hours
Note that DTT is stable in aqueous solutions < pH 7.6, but degrades rapidly at higher pH.

[NattyB]

Thank you very much, ill just make stocks of each component and and DTT on the day