Hi. We have been using His-Select Resin from Sigma in our lab for a number of years now. When we first bought the resin, I usually got much better purity of His tagged proteins compared with regular Ni-NTA resin. However, after regenerating the resin several times, the level of purity seems to have declined. Has anyone else noticed this with His Select? In general, could someone suggest the typical "lifespan" of His Select or Ni2+ resin in general? What about Glutathione resin?
I was also wondering if anyone had experience using cobalt resin? What is the binding capacity of cobalt compared to nickel, and is the selectivity any better than either His-Select or regular Ni-NTA? Also, is it possible to just strip nickel off of the resin and then recharge it with cobalt? Thanks, Matt
