Dear all,
Sorry for the off-topic question, but I am really curious why two
terminal residues could make such huge difference.
I am working on a all helical domain starting from residue 1 to about
130. It expressed well with N-terminal His tag in both E.Coli and
insect cell, but stayed insoluble in both hosts. The fusion of N
terminal MBP tag could produce soluble form, but the target protein
precipitated immediately after cleavage of MBP. I tried several
constructs ending at different C-terminal residues, but none helped.
However, when I truncrate the N-terminal residues one by one, the
deletion of Met1 and Ala2 turned this protein into almost "completely"
soluble (30mg yield per liter E.coli cultue), and it behaved good
after cleavage of N-terminal His tag. In homologous structures, the
first helix starts from the third reidues.
So my question is what property of the protein might have been
affected by the first two residues, the surface hydrophobicity, the
folding process, or something else?And would this one-by-one
truncation of N-terminus be commonly helpful when working on insoluble
small proteins?
Thank you!
Best regards,
Tiancen
Postdoctoral Fellow
Novartis Intitutes for Biomedical Research
250 Mass Ave
Cambridge
MA 02139
U.S.
