From: John Correia <jcorreia@biochem.umsmed.edu>
  To  : rasmb@alpha.bbri.org
  Date: Tue, 22 Jun 1999 15:24:12 -0600

low MW

More information is required to give you feedback:

1 - - nonideality effects reduce Mapp.

            At what concentration did you do the run?  

            What is the calculated charge on the peptide?  What is the pH
of the solution?  What is               the ionic strength and does it
swamp the charge effect?

2  --  How did you estimate vbar and density?  Measure density to remove
uncertainty!  How much of an error in vbar would account for the effect?

3  - -   Is the fit to a single species a good fit?  Are you sure you have
no lower MW contaminants?  Gel filtration confirms sample purity?

4  - -  What optical system are you using?  Misalignment can, possibly,
cause deviations from ideality.


-------------------------------------------------------------------
 Dr. John J. "Jack" Correia
 Department of Biochemistry
 University of Mississippi Medical Center
 2500 North State Street
 Jackson, MS  39216
 (601) 984-1522                                 
 fax (601) 984-1501                             
 new email address: jcorreia@biochem.umsmed.edu     
 homepage: http://fiona.umsmed.edu/~biochem/correia.html  
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