Which His Tag Length, Position or Sequence to use?

Length and position of HisTags can affect the following:

  • Expression Yield
  • Efficiency of translation. Triplet codons located after ATG can inhibit translation. Use highest expressing AAA (Lysine) at position 2
  • Binding to IMAC resin
  • Results (activity, crystallization, NMR …etc). Remove the tag!
  • Oligomerization state

E.coli water channel AqpZ expression and purification using different His-Tags (Co = cobalt-IMAC, & subsequent Q2= ion-exchange).