pKa of amino acid residue in enzyme

ChenHA Hzhen at freeuk.com
Wed Mar 27 10:42:48 EST 2002


Chris wrote:
> 
> Hi
> 
> I have a histidine which I believe is acting as a base to abstract a proton
> from  a cysteine at the active site of an enzyme I am working on and was
> wondering if anyone knew of any ways to measure the pKa of either the
> histidine and/or the cysteine (preferably not by NMR) . I do have alanine
> mutants of both the cysteine and histidine if those are at all useful in this.

Many people have used lots of different methods for determining pKa, for
example, using spectrometric methods such as UV, infra-red, Raman
spectroscopy, or you can use enzyme kinetics, or even use X-ray
crystallography.  However, I don't know what you have against NMR, since
it is actually the most accurate way of determining pKa.  
 




> 
> Thanks in advance for your help
> 
> Chris
> 
> <http://www.biowww.net/forum/read.php?f=6&i=984&t=984>




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