I believe that there is usually enough zinc in complex growth media to supply the overexpressed protein, so it is not necessary to add it, if it is a tightly bound or structural zinc. If it is not tightly bound, then it will probably be absent or partially absent in the purified protein, and you will have to add it to the activity assay.

If your protein uses Zn as a co-factor, can not you add ZnCl to the reaction medium when your protein will be used as a catalyst?

I believe that there is usually enough zinc in complex growth media to supply the overexpressed protein, so it is not necessary to add it, if it is a tightly bound or structural zinc. If it is not tightly bound, then it will probably be absent or partially absent in the purified protein, and you will have to add it to the activity assay.

Thanks to all of you for suggestions!

Hello,

As far as my experience with rosette and expression of protein is concern, there is no need of adding ZnCl....you can directly do induction with IPTG.

Good Luck.......

I was working with protein containing zn finger domain. I never used additional Zn in growth media. There is enough of zinc in the media.

There is typically enough zinc present in the medium to ensure proper functioning of the protein. However, depending on how you might want to purify this protein, especially IMAC, you may have to add back zinc later, especially if steps involving denaturation/renaturation or use of EDTA containing buffers are involved. I have found that addition of zinc after purification can dramatically improve activity of proteins that require zinc as a cofactor. Futhermore, if purifying with IMAC then the nickel or other divalent metal ion used for the affinity purification can interfere with zinc binding and inhibit protein activity. Please see my publication (attached) for a detailed discussion of exactly this issue.