[RASMB] upper concentration limit AUC

[Christine Ebel]

Dear Joris, dear all, 

This reference may be perhaps useful.

 

Solovyova A., Schuck P., Costenaro L., Ebel C,

Non-ideality by sedimentation velocity of halophilic malate dehydrogenase in
complex solvents, 

(2001) Biophys. J, 81 1868-1880.

 

In this work, we analyzed sedimentation velocity profiles considering
hydrodynamic and thermodynamic non ideality. (i.e. concentration dependency
of s and D) in the case of an homogeneous  solution of our protein of
interest. The modified Lamm equation was implemented in a model of analysis
in Sedfit (note that, unless the programme was recently modified, the kS and
kD are expressed in signal unit in sedfit)

>From my experience, the sedimentation velocity profiles are essentially
modified by the concentration dependency of the sedimentation coefficient.
Thus the concentration dependency of D can be neglected in a first
approximation. Also from a theoretical point of view, kD is much lower that
ks. 

All the best

Christine 

 

Christine EBEL

Institut de Biologie Structurale CEA-CNRS-UJF

41 rue Jules Horowitz, F-38027 Grenoble France

Tel (33) (0) 4 38 78 95 70; Fax (33) (0) 4 38 78 54 94 

christine.ebel at ibs.fr

 <http://www.ibs.fr/content/ibs_eng/presentation/lab/lbm/ebel.htm>
http://www.ibs.fr/content/ibs_eng/presentation/lab/lbm/ebel.htm

-----Message d'origine-----
De : rasmb-bounces at rasmb.bbri.org [mailto:rasmb-bounces at rasmb.bbri.org] De
la part de Beld, Joris
Envoyé : lundi 1 septembre 2008 15:24
À : RASMB at rasmb.bbri.org
Objet : [RASMB] upper concentration limit AUC

 

Dear all,

 

A colleague asked me whether analytical ultracentrifugation has an upper
limit with regard to the concentration of the protein. They want to measure
the protein at the same concentration as the NMR experiments (> 1 mM). I am
not entirely sure but I thought this should be no problem. One could easily
measure off-peak at another wavelength than 230nm, e.g. 235nm or 280nm,
right?! Or does one run into non-ideality phenomena when doing sedimentation
equilibrium at these high protein concentrations?!

Thanks a lot in advance for any feedback.

Best wishes,

 

Joris Beld

 

Hilvert Group

ETH Zürich

Switzerland

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