[ccp4bb] add ligand solution onto drop directly SUMMARY

[Markus Heckmann]

Thanks for the responses. Yes, my crystal did survive and I can see
density for my ligand.

Summary:
1. If the crystal survives, it’s fine. These are just different ways
of exposing the crystal to the ligand and do what works. The only
issue will be if you don’t see electron density for the ligand in your
structure. If you just add ligand to the drop then there is plenty of
other precipitate/stuff that could non-specifically bind to the ligand
and reduce the amount available to bind the protein in the crystal. So
if you don’t see density, it would still be worth soaking a “clean”
crystal in the ligand/precipitant solution.

2.  It is OK as long as your crystal survives. I do this regularly, or
even just add dry compound to the drops directly, usually after adding
more reservoir to make the drop a bit bigger. It seems to work fine
for some compounds, not for others. It is very empirical.

3. The truth is in the map. Ergo, zap it and rationalize why it worked
or not later.

Re: [ccp4bb] add ligand solution onto drop directly

[Bernhard Rupp]

The truth is in the map. Ergo, zap it and rationalize why it worked or not 
later.

 

Cheers, BR

 

From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of Markus 
Heckmann
Sent: Tuesday, January 24, 2017 6:23 PM
To: CCP4BB@JISCMAIL.AC.UK
Subject: [ccp4bb] add ligand solution onto drop directly

 

Dear all,

I wondered if it is OK to pipette ligand soln (X-CoA) *directly* to the drop 
with crystal (1:1 ratio of protein:precipitant 2µl) instead of dissolving it in 
precipitant solution and transferring the crystal to this ligand containing 
precipitant solution. The crystals survive this as I add the ligand solution to 
the edge of the drop and gently mix the two solutions. Since I collected my 
datasets I wonder if it is OK?

Many thanks,

Markus

[ccp4bb] add ligand solution onto drop directly

[Markus Heckmann]

Dear all,
I wondered if it is OK to pipette ligand soln (X-CoA) *directly* to the
drop with crystal (1:1 ratio of protein:precipitant 2µl) instead of
dissolving it in precipitant solution and transferring the crystal to this
ligand containing precipitant solution. The crystals survive this as I add
the ligand solution to the edge of the drop and gently mix the two
solutions. Since I collected my datasets I wonder if it is OK?

Many thanks,
Markus