[RASMB] DDT, detergents, and reference intensities

[HOLLADAYL at aol.com]

Hi all;

the disulfide chromophore has an extinction coeifficient of around 110 at 
280.  Now if one has 200 mM DDT, and 10% is oxidized, then one has a 
background buffer absorbance of 2.2 at 280.

My counsel is to always run a bench top absorbance scan of both buffer and 
sample if it is a sample given to you.  I think all of us have horror stories 
of hysterical samples.

As for detergents,  I've seen problems with sed eq data at higher speeds when 
the micelles redistributed enough to throw the light beam off center towards 
the bottom.

There is no substitute for looking at the intensity of the reference sector 
for equilibrium absrobance scans.  This will tell you the story.  I take 
credit for this being in the Beckman acquisition software.

best regards

Les Holladay

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