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  From: Borries Demeler <>
  To  :
  Date: Wed, 3 Jun 1998 07:34:24 -0500 (CDT)

Hepes and Pipes buffer values

Dear RASMB'ers,

I am looking for buffer data (density and viscosity) for pipes and hepes 
buffer for inclusion into the sednterp database. Does anybody have the 
values or measured these over a useful concentration range?
The appropriate polymomial fit coefficients would work also. Thanks!

 Borries Demeler
 The University of Texas Health Science Center at San Antonio
 Dept. of Biochemistry
 7703 Floyd Curl Drive
 San Antonio, Texas 78284-7760
 Voice: (210) 567-6592
 Fax:   (210) 567-4575
From  Wed Jun  3 10:28:13 1998
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Date: Wed, 03 Jun 1998 10:33:51 -0500
To: Borries Demeler <>
From: jack correia <>
Subject: Re: Hepes and Pipes buffer values
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Status: RO


	We have done Pipes from 10 to 400 mM complete with fits etc at 25oC.
However, we then did temperature work (4-37oC) at 10 and 100 mM and
compared it the changes in water.  The deviations are, not surprizingy,
large and get larger at higher concentrations.  Thus we plan to investiagte
it in a systematic way and come up with a better set of data that takes
into account effects of [Pipes] on density and its temperature dependence.
Then we planned to hand the data over to Tom for a different incorporation
into sednterp.  We also have done EGTA and MgSO4 since we use commonly use
them in our buffers, but the same problem must be dealt with.  I am willing
to put the data and fits out there before we solve the problem since the
rest of the data set is done in the same way, but we did it at 25, not 20,
so incorporation immediately introduces error.

	This means the entire density (& viscosity) data set incorrectly corrects
for temp.  Our solution for density is to measure the actual buffer at the
experimental temperature since we have a new Anton Paar with a 0-80oC
range.  Viscosity is another question since it takes much longer to do and
its not so easy to vary temperature baths over that range for a viscosity
measurement.  I suspect therefore we will only do density.

 Dr. John J. "Jack" Correia			 
 Department of Biochemistry                    
 University of Mississippi Medical Center       
 2500 North State St.                           
 Jackson, MS 39126                              
 (601) 984-1522                                 
 fax (601) 984-1501                             

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