From: John Correia <jcorreia@biochem.umsmed.edu>
  To  : smorris@medusa.bioc.aecom.yu.edu
  Date: Thu, 26 Jul 2001 16:49:06 -0500

Re: small peptides

Richard Thomas in Switzerland has been looking at coiled-coil formation of
small peptides for years - search his name or ask him directly at
rthomas@ifp.mat.ethz.ch 

Difficult problem because evan at 60 K a 2000 dalton peptide only has a
reduced MW (sigma) of ~0.88 (depending upon vbar and density) meaning very
little curvature - thus difficult to fit - always use sednterp to estimate
sigma in advance to choose the best speed and alsways always do lots of
loading concentrations to help convergence.  In this case more samples may
work better than multiple speeds because slower speeds are even less well
determined.  Also Peter Schusk has published a velocity approache,
essentially an Archibald, for small peptides.  My suggestions is again use
more than one sample.

An additional problem is the usual lack of trp and tyr so measurements
must be made at 220 or with interference.

Don't be too despondent about prospects - Dave Yphantis one measure the MW
of air, that is a vacumn in the ref and air in the sample experiment, and
got the right answer.


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 Dr. John J. "Jack" Correia
 Department of Biochemistry
 University of Mississippi Medical Center
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