Hi Nicola,
I would just add zinc solution to the protein before the crystallization
and/or to the drop with crystals.
An important thing to keep in mind is that Zn salt solutions will have
low pH, unless a sufficient buffer is used.
I recommend having a look at the article
"Characterizing metal-binding sites in proteins with X-ray crystallography"
https://www.ncbi.nlm.nih.gov/pubmed/29674755
With best regards,
Ivan Shabalin, Ph.D.
Research Scientist,
Department of Molecular Physiology and Biological Physics,
University of Virginia,
1340 Jefferson Park Avenue, Pinn Hall,Room 4223,
Charlottesville, VA 22908
https://www.linkedin.com/in/shabalinig/
https://minorlab.org/person/ivan_s/
On 12/9/18 16:31, Nicola Evans wrote:
From a fluorescence scan it would appear a protein I am working on has zinc in
it. The occupancy is likely to be very low however (a structural homologue has
several zincs in the x-ray crystal data but at 0.5 occupancy), as there isn't
anything obvious in the electron density map (perhaps some of the waters are
zinc) and an anomalous difference map wasn't possible to obtain on our last
beamtime.
Ideally I would want to re-express the protein with zinc added to the culture
conditions, but I am time-restained, so I was wondering if it is possible to
add zinc to purified protein instead? I have heard it can cause proteins to
crash out. I have quite a lot of protein frozen so I can try a few things. I
would appreciate any advice on how much to add from anyone who has had success
with this before?
Thanks in advance!
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