Thanks for all who shared their experiences. I received some
personal and public suggestions/comments. So, time for a summary now.
My original question was about the influence of his-tag and
c-myc-tag on crystallization.
Concerning His-tags: some opinions differ, a brief summary of the points
raised are
- in some cases important for crystallization
- choose a method at the start to take out the tag, yet it is more
likely to crystallize without it.
- cases where crystals came only with his-tag, but also the opposite,
either crystals (or better crystals) without his-tag.
- a recall that it is not all that difficult to cleave; also,
recommendation to check 3C protease and His-SUMO tag ideas, other
recommendation, look into the Tagzyme kit.
- sometimes His-tags might make the protein prone to aggregation. Also,
might bind cations at high pH's (might set up crystal contacts)
I see some recommendations/comments: you have the his-tag, go to it
first, consider taking out the tag if crystallization trials were
unsuccessful. That is a standard in some groups.
But..., no one commented about c-myc tags. As I expected, there is
no experience with this one yet - ?
Jorge
