IUBio Biosequences .. Software .. Molbio soft .. Network News .. FTP


Achim Recktenwald achim at ibex.ca
Tue Jul 23 15:07:53 EST 1996

Martin Offterdinger wrote:
> In article <Pine.SOL.3.91.960716142607.28951C-100000 at godzilla4.acpub.duke.edu>, Namjin  Chung <nc1 at acpub.duke.edu> says:
> >
> >
> >Dear Netters,
> >I'm working with an uncharacterized yeast enzyme activity, and it seems
> >to have activity around pH 2.5 and 3.0.  Currently I'm using Citric Acid
> >and Citrate-Phosphate buffers to get a decent result.  The activity is,
> >however, inconsistent-standard deviation is high from experiment to exp.
> >
> >I guess that harsh pH like 2.5 itself might have killed the enzyme
> >activity to give varying results, but is that possible?  If pH itself
> >were the matter here, it should always kill the enzyme, and if there is
> >the enzyme activity around this pH, the enzyme should survive at this pH.
> >
> >So I suspect the buffers (citrate and citrate-phosphate) may not be good
> >at this pH.  Is there anyone who had this kind of experience, and/or who
> >could recommend a good buffer for this pH range (2.5-3.0).  Thank you in
> >advance for comments.
> >
> >PS: Please send an email to me in addition to posting to the newsgroups
> >if you will do so.
> >
> >************************************************************************
> >* Namjin Chung                             *                           *
> >* Program in Molecular Cancer Biology      * Email: nc1 at acpub.duke.edu *
> >* Duke University Medical Center, Box 3345 * Voice: +1 (919) 684-2363  *
> >* Durham, NC 27710                         * Fax  : +1 (919) 681-8253  *
> >************************************************************************
> >
> Dear Nmajin,
> Have you tried Glycine/HCl , this system is good for preparing acidic buffers.

Is the pH 2.5 the pH-optimum for the enzyme's activity, or did you just try if the 
enzyme works at that pH ?
In the latter case, your enzyme could be somewhat stable at pH 2.5, but loose its 
activity slowly, that means the deactivation is slow enough for you to do siome work 
with the protein before it is dead. 

Glycine/HCL is the better buffer in this range. Citrate  has the additional effect 
of chelating metal ions. If your enzyme needs some metal ion, the loss of activity 
could be a sign of its removal.


More information about the Yeast mailing list

Send comments to us at biosci-help [At] net.bio.net