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
Hi Nicola,
We have had success simply soaking zinc into the crystal prior to data
collection. This has worked very well for a number of proteins. We simply add
some zinc to the cryo-protectant and leave it to soak for various times.
Hope this helps.
Kind regards
Sheena
Sheena McGowan
Hi Nicola,
One way to do it is to dilute your protein, 10-100 times, and add zinc (also
diluted), then concentrate.
Here is the procedure we used some time ago for a zinc-binding protein:
“S100A12 was diluted to 0.1 mg/ml-1 (approximately 10 mM) in a buffer
containing 20 mM Tris-HCl pH 7.5,
Hi Nicola,
If all you are looking for is evidence that you have zinc in your structure
based on the anomalous difference map, then with the data you already have you
should be able to calculate the anomalous difference map! All you have to do is
to reprocess the data in anomalous mode or
Dear Eugene,
the additive is a metal-polyanion with a net charge of 6- ... yes, NaCl
affects largely the solubility of the anions, however, the LLPS appears
within a rather large protein concentration range (10-50 mg/ml = 0.7 -
3.5 mM) in the presence of e.g. 0.1, 0.5, 1.0, 2.5 and 5.0 mM
