Conditions prone to salt crystallization: Difference between revisions

Conditions prone to salt crystallization (edit)

1,218 bytes added , 17 February 2011

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+<td>Hampton stockoptions salt as additive </td>
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+<td>NaF >0.24M, 100mM sodium citrate pH<5.6 </td>
-<td> </td>
+<td>20 mM Tris, 150 mM NaCl, 5 mM DTT </td>
-<td> </td>
+<td>Yes </td>
-<td> </td>
+<td>I would expect NaF to be more soluble at low pH (if anything) because of a secondary equilibrium with HF. Nothing in the reservoir, only in the drop; anything under 5.6 gives a few hexagons. If equilibration is slow it will give thick birefringent rods. I'm thinking even minimal contamination by phosphate could give rise to something like fluorapatite, since NaF crystals would be cubic I would think. I have also seen higher concentrations of ammonium fluoride cause the drop to spread all the way over the cover slip and give rise to concentric rings of hexagons (NH4F is actually a hexagonal crystal though as opposed to NaF). Glass etching due to insufficient siliconization? Anyway, beware fluorides in general</td>
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+<tr>
+<td>Nextal Classics #6
+= Hampton Crystal Screen #24</td>
+<td>0.2M CaCl2, 0.1M Na acetate pH4.6, 20% isopropanol</td>
+<td>20 mM Tris, 5 mM DTT </td>
+<td>Yes</td>
+<td>Nice-looking crystals observed for two different proteins.  I suspect DTT may play some part.</td>
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+<td></td>
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+<td></td>
+<td>Make a copy of this row for the next person to fill in</td>
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