apparent size shift in SDS-PAGE

John Berges J.Berges at Queens-Belfast.AC.UK
Mon Jan 27 03:17:24 EST 1997

Hi Folks,

I have been perfoming some experiments applying different environmental 
stresses to marine algal cells and measuring a number of responses, 
including changes in protein profiles on silver-stained SDS-PAGE. 

In several specific cases I have noticed a phenomenon where a number of 
lower MW (20-40 kDa) proteins in stressed cells seem to 'shift' to lower 
MW on the gel (say 6-10 kDa lower, relative to controls).  At first I 
thought this was a gel artefact, but it is consistent and reproducible. 
 The extracts are TCA/acetone precipitated, so I have difficulty 
believing it is an effect of some other compound produced by stressed 
cells.  I have considered the idea that it is some sort of proteolysis 
producing lower MW fragments, but if so, it is highly ordered.  The new 
bands maintain a similar size-relationship and density relative to each 

Any thoughts or comments would be much appreciated. 

     _/_/_/_/  _/    _/ _/_/_/   Dr. John A. Berges
    _/    _/  _/    _/ _/    _/  Biology and Biochemistry
   _/    _/  _/    _/ _/_/_/     Queen's University, Belfast
  _/  _/_/  _/    _/ _/    _/    BT9 7BL Northern Ireland 
 _/_/_/_/  _/_/_/_/ _/_/_/       FAX: 44 (0)1232 236 505 

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