SDS-PAGE problem!

[arturo.galvani at itner.pharmacia.se]

     Wei Zhao (WZhao80850 at aol.com or weiz at protein.bchs.uh.edu) wrote:
     
     >Hello there,
     >I post about the same question about a month ago, until now I haven't 
     >got any creative suggestions and also could not solve my problem by 
     >myself. I am frustrating here. I problem is:
     >I am using BIO-RAD mini-gel electrophoresis system. My target protein 
     >is about 25-27 KD. I run 12% running gel and 4% stacking gel at 100 
     >V. The results I've got were curved and connected bands between 
     >lanes. First I thought it might cause by high salt concentration in 
     >my sample, I diluted my sample from 5 ug/ul to 3 ug/ul.The results 
     >got better but not good enough. I still had curved bands and 
     >connections between lanes. It seems like both ends of the bands 
     >migrate faster than the middle. 
     >Could anybody give me some advice? Thanks in advance! Cheers!
     >Wei
     
     -Do your markers run O.K.?
     -How much protein are you loading/lane? (0.5 ug/lane is more than    
      enough for a minigel stained with Coomassie).
     -What's the [salt] in your protein prep?
     -Is the sample pH O.K. (i.e. 6.5-7)?
     -Do you have any gunk (e.g. DNA) in your sample?
     
     Arturo Galvani