From: Geoff_Howlett.BioChem@muwaye.unimelb.edu.au
  To  : rasmb@bbri.eri.harvard.edu
  Date: Thu, 08 Jun 1995 09:12:32 +1000

Re: Acetonitrile

Thank you to all who responded to the question of acetonitrile.  The basic 
observation was that a sample repurified by reverse-phase HPLC was cloudy 
and a proportion of the material floated during low speed centrifugation. 
 A summary of some of the responses:

Richard Thomas	"We runs a lot of proteins/peptides which have been 
purified by HPLC using acetonitrile...".  Suggests two 
possibilities-bleeding of the reverse phase from the column or an 
AN-binding protein?

John Philo		"the lore at Amgen is that freeze drying 
definitely does not remove all the TFA but the acetonitrile should go"  
Misfolded proteins could cause problems with aggregation.  Can get carry 
over from aqueous work which causes cloudiness when you switch back to 
reverse-phase

Arthur Rowe	"recombinant proteins usually have some ill-assembled 
garbage.. which may bind AN to the hydrophobic bits"  Maybe flotation 
separation could have a commercial application here...  We can get 
wealthy?

Take home lesson:

Beware the cloudy sample.  At this stage the possibility of residual AN, 
bleeding of reversephase from the column and possibly oil mist from the 
freeze-drier remain as candidates for further investigation.

Thanks again

Best to all

Geoff Howlett
Department of Biochemistry and Molecular Biology
University of Melbourne
Parkville 3052
Australia

FAX	61 3 9347 7730
PH	61 3 9344 7632

E-mail:	g.howlett@biochemistry.unimelb.edu.au