extra bands on SDS PAGE gel - (Oct/31/2007 )

hi all! i have successful expressed my protein for about a yr now. recently however i have upscaled the reaction (only to 1L!) and have had to change my buffer for concentrating in as the protein precipiated out. the composition of this buffer is as follows: Tris Hcl 50mM
DTT 1mM
NaCl 150mM
Mgcl2 1mM
Now i am getting two bands on my SDS PAGE gel (normally had only 1 at 25kDA) at 25kDA and 50kDa. homologs of this protein has been known to form a dimer. any ideas if this is what is happening here or is there something ive missed that has gone wrong??

I think as per your information it might be dimer.

I am guessing its the dimer too

I make a bet you have dimer formation