[RASMB] buffer components and IF optics

[Irene Hallyburton]

> 
> Regarding high concentrations of DTT, I have no hands-on experience
> with this situation in particular, but if it's not possible to
> precisely match the sample and reference sectors in the buffer
> composition, you'll see the sedimentation of DTT.  Also, I'm not sure
> if the refractive index increment of DTT could possibly change with
> oxidation state, and in this way create a mismatch between the two
> sectors.  But again, it should be no problem to take this into account
> in the data analysis (assuming that you have an excess signal from DTT
> in the sample sector), by treating this as an extra sedimenting
> species.
> 
In my limited experience I have come across one problem with DTT. A Student supplied 
me with a sample and buffer containing 1mM DTT for an SV run. On the 3000rpm run all 
I saw was noise. Initially we thought  azide was the problem, but it turned out to be 
oxidised DTT. This was  solved by adding the same concentration of TCEP.

Irene