Hi Dr. Gaur,
A few questions:
1. Do you know the kinetics (binding constants, etc) of the drug and the
protein?
2. Do you know how soluble the drug is in DMSO (is 10 mM the most
concentrated?)
3. Is the drug soluble in a mixture of DMSO and water (70% DMSO)?
4. Have you tried crystal soaking experiments?
DMSO can poison crystal formation and it can also enhance it as an additive as
well as a cryoprotectant. You’ll have to determine how much DMSO you can add
and still obtain diffractable crystals under 2.5 Å.
My suggestions would be:
* Take an apo crystal and transfer it to a drop with the amount of DMSO you
plan on adding in your mother liquor and observe (does it wiggle, did it
dissolve, does it still diffract?)
* Grow your apo crystal in the presence of DMSO and shoot it (did the
crystal grow, diffract, etc)
* Get the most concentrated sample of your compound and do
* Co-crystallization experiments
* Soaking experiments
* If DMSO is donking up your experiment, try a different solvent, or a
lower concentration of DMSO in water.
Best,
eta
***
Eta A. Isiorho, Ph.D.
Research Assistant Professor
Macromolecular Crystallization Facility Manager
CUNY Advanced Science Research Center
85 Saint Nicholas Terrace, 3.352B/3.134
New York, NY 10031
eisio...@gc.cuny.edu<mailto:eisio...@gc.cuny.edu>
From: CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> on behalf of amit gaur
<cdriamitg...@gmail.com>
Date: Wednesday, October 2, 2024 at 2:51 PM
To: CCP4BB@JISCMAIL.AC.UK <CCP4BB@JISCMAIL.AC.UK>
Subject: [ccp4bb] Co-Crystallization with drug molecule
Hi everyone,
I am trying to crystallize a protein with a drug molecule. The protein
concentration is 15.5 mg/ml, the drug stock concentration is 10 mM, and the
drug is dissolved in DMSO. I am adding the drug to a final concentration of 1
mM in 100 ul of protein, and the DMSO volume is 10 ul for Co-crystallization. I
want to know how much DMSO is permissible during co-crystallization with the
drug and if DMSO can poison crystal formation. I have not been successful in
getting crystals with inhibitors till now, but I obtained crystals of protein
without DMSO, and those diffracted to 2.5A.
Thanks,
Dr. Amit Gaur,
Research Scientist
Center for Biotechnology and Interdisciplinary Studies,
Rensselaer Polytechnic Institute,
1623 15th Street, Troy, NY, 12180
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