[RASMB] Centrifugal force and protein dissociation

[JA KORNBLATT]

On Tue, 23 Jul 2002, Songpon Deechongkit wrote:

> Date: Tue, 23 Jul 2002 19:54:14 -0700 (PDT)
> From: Songpon Deechongkit <songpon at scripps.edu>
> To: rasmb at rasmb-email.bbri.org
> Subject: [RASMB] Centrifugal force and protein dissociation
> 
> ----------------------------------------------------------------------------------
> The older archived RASMB emails can be found at:
> http://rasmb-email.bbri.org/rasmb_archives
> and current archives at
> http://rasmb-email.bbri.org/pipermail/rasmb/
> Search All the Archives at:
> http://rasmb-email.bbri.org/rasmb_search.html
> ----------------------------------------------------------------------------------
dear songpon
the old data on yeast enolase indicated that it underwent dissociation at
high velocities. gregorio weber and paladini reasoned that it did so
because of the pressures built up at these speeds.     accordingly, they
put enolase under pressure and it dissociated. if you are working at
velocities around 40 krpm, you might be developing as much as 6 MPa at the
bottom of the cell. if you are going up to 60 krpm, it might b e as much
as 30 MPa at the bottom. 
whether these pressures bring about dissociation is a function of the
equilibrium coefficient at 0.1 MPa and the volume change that
occurs on dissociation. 
hope this helps
jack kornblatt

> 
> Dear colleagues:
> 
> Currently, our lab has tried to determine the heterogeniety of an old
> protein sample.  The protein, if folded correctly and behave well, should
> remain tetrameric for a long time.  However, by sed. Vel. we found that
> the protein sample is the mixture of monomer, dimer, and tetramer.  The
> fit was done by DCDT (by John Philo).  Here are a few questions that I
> would like to ask:
> 
> 1)  Can centrifugal force tear multimeric protein apart?  This protein, in
> particular, has a central channel where water can go through.
> 
> 2)  If there is monomer-dimer-tetramer equilibrium, can we trust
> sedimentation velocity data in terms of their relative amount?
> 
> 3)  What is the reliability or error from the sed. Vel. fit?
> 
> We are very confused whether the fact that we observe
> monomer-dimer-tetramer is true or is just an artifact.  I would greatly
> appreciate your insight, thought, or suggestion in light of these
> concerns.
> 
> Sincerely yours,
> Songpon Deechongkit
> PhD Candidate
> Jefferey W. Kelly Lab
> The Scripps Research Institute
> La Jolla, California
> 
> 
> _______________________________________________
> RASMB mailing list
> RASMB at rasmb-email.bbri.org
> http://rasmb-email.bbri.org/mailman/listinfo/rasmb
>