[RASMB] Chris comb. Origin-Beckman and Segal

[Lustig]

Dear  colleagues, dear Chris,     (repeat send)
I like to thank you indeed for the effort loading our Segal program and 
combine it  with Beckmans  Origin.
I like also to mention again that Segal was written and elaborated by Gia 
and me (Dr. Gia Machaidze
 >>Gia.Machaidze at unibas.ch<<) He makes the programming work and I have the 
AUC . Soon it will possible
to use  Segal also for  the  6 channel mode.

Luckily  I have  no idea , about  your calculated  minimum  Mw, self 
association? complex of...etc....
 From  the  curve fragments as  you have  compaired  with  both  programs , 
it seems that  the  Mw rises with
the  concentration , at least at the lowest  concentration it dissociate 
or  there are lower impurities at small
prot concentrations?
The relative correlation  of the total  measured range is not so good 
=0.999407 but
using *knob sensitive* I divided  from 6.92 - 70.7= 45 Kda  0.999737corr. and
                                                                  7.001- 
7.141 =  70 Kda   0.99996 corr.
The lower  part  of about 45 KDa show clearly on your edited radial part, 
that the points forms a convex  distribution
and the  70 KDa  part  a concave one. This stem  from the  logarithm bad 
adapted absorbance level (=baseline).
With  my  2 parts,  at least  the  higher conc. part is much better 
correlated. The lower  part is more sensitive  ,
because  the signal is low (nearly depleted) and suffers from  the relative 
noisy line.
My propose especially  for a self associated  system , to fill several 
cells  with  a filling  height of about 2 mm with
different concentrations or cell thickness ( we have 2.,3,4and 12mm) and to 
run them  at different rotor speeds so that for each cell the mid of the 
filling column  is close  to the initial  conc. or  OD. So you  can 
prevent  to scan low  signals (OD's) with high noise ratio  as the  45kDa 
example shows. From few  conc's you can nicely draw  a conc.depend graph 
without artifacts.
Your extreme  long filling height and relative high speed is close to the 
high speed mode (called also meniscus depletion
mode) has the  disadvantage  that  near the cell bottom you may  enter in a 
non-ideal region, and for each conc region
you have  only a short  radial distance for calculation.

Returning  back to the given run. If  the 4 chosen  sectors are part  of  a 
self-association I don't  see the different Mw's
as a discrepancy, but  if  from my 2 chosen parts the lower one as  I 
said  includes other  impurities, it is nice to
see them.
You sure know more than my guess ....ariel
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