Successful complexation depends on the concentration of protein, ligand, and the Kd of the protein-ligand complex. For Kd>>[protein], you will probably require [ligand] > 10 x Kd. As Kd approaches [protein], slightly superstoichiometric quantities will be sufficient for full occupancy. For Kd < [protein], stoichiometric quantities of ligand will suffice. Basically you need a [ligand] that puts near saturation on the binding isotherm.
From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of Roger Rowlett
Sent: Thursday, August 25, 2011 6:11 PM
To: [log in to unmask]
Subject: [ccp4bb] Fwd: Re: [ccp4bb] co-crystallization
Cheers.
On 8/25/2011 2:03 AM, Yvonne TAN Yih Wan wrote:[log in to unmask] type="cite">Hi ,
I am co-crystallizing a protein with compound and would like to know how much of compound to add to protein solution to start with. I know that the protein binds compound in a 1 to 1 ratio but also noticed that the compound precipitates out of solution when DMSO is diluted off. Where should I start of? A 1 protein :2 compound ratio or more? And what is the best method to determine if the binding is homogeneous (that all protein has got a compound in it)?
Any suggestions would help. Thanks
TY
--
Roger S. Rowlett
Gordon & Dorothy Kline Professor
Department of Chemistry
Colgate University
13 Oak Drive
Hamilton, NY 13346
tel: (315)-228-7245
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