Quick navigation:        Home   |    Site Map   ||    References   |    Biography   ||    Copyright   |    Other copyright   |    Contact us   |   
Protein structure
 

Re: [ccp4bb] Malic Acid interferes heavy metal binding?
 

Basic tutorials: 		 
 

CCP4bb navigation

CCP4bb <-- 2008 <-- January 2008 <-- 09 January 2008
Previous message:
Subject: Malic Acid interferes heavy metal binding?
From: JINJIN ZHANG zhang {- dot -} 508 {- at -} OSU {- dot -} EDU
Date: 2008-01-09 		Next message:
Subject: Re: Sulfate ion on 2-fold axis
From: Charlie Bond Charles {- dot -} Bond {- at -} UWA {- dot -} EDU {- dot -} AU
Date: 2008-01-09


Subject: Re: Malic Acid interferes heavy metal binding?
From: William Scott wgscott {- at -} CHEMISTRY {- dot -} UCSC {- dot -} EDU
Date: 2008-01-09
Dear Jinjin:

Malic acid, a diprotic acid, has a pKa of about 3.4 for the first dissociation and a second at about 5.1. So it is best as a buffer within a pH range of about 2.4 to 6.1, and it at its best around best in the range of 3.4 to 5.1. If the pH of your solution is indeed 7, then it is doing little to buffer it (but the small amount of tris might).

Many diprotic and polyprotic organic acids chelate metal ions.

If you could substitute a different dianionic salt in the mother liquor, like a sulphate, it might help.

Bill



On Wed, 9 Jan 2008 18:42:06 -0500
JINJIN ZHANG wrote:

Dear All,

I have got large and nice crystals in a condition that contains 40% glycerol, 75 mM DL-Malic Acid pH7.0, and that's it! No precipitant?! No buffer?! I'm so comfused. As far as from the product website, the Malic Acid has no buffering function. I don't know whether it's a precipitant. The protein itself was stored in a buffer contains 20mM Tris pH7.5, 150mM NaCl and 10% glycerol. I'm having difficulties in getting heavy metal bound derivatives. I was wondering whether the Malic Acid interferes heavy metal binding? Does anyone has any success with crystals grow with similar conditions? Any comment and suggestion is highly appreciated.

Regards,

Jinjin Zhang
ProteinCrystallography.org: Copyright 2006-2008 by Quid United Ltd