A Practical Guide to the Preparation of Ca Buffers - Methods in Cell Biology - page 20

MaxChelator series of programs, first introduced in the 1994 version of this
chapter.
There was no internet 16 years ago when the first edition of this chapter was
presented. The compilation of useful stability and thermodynamic constants (e.
g., Martell and Smith, 1974, 1977 ) has not grown with the explosion of biological
use of Ca 2 þ bu

ers and novel Ca 2 þ indicators (although resources are available
at the National Institute of Standards and Technology (NIST) web site http://
www.nist.gov/srd/nist46.htm ) . For most of these new compounds, accurate sta-
bility constants have not been determined. Further, there is some disagreement
over which constants and algorithms are best. However, as implied above, it is
valuable to be able to calculate appropriate stoichiometric concentrations of, for
example, Ca 2 þ ,Mg 2 þ , EGTA, and ATP to use in your solutions to obtain the
desired free [Ca 2 þ ]and[Mg 2 þ ]and[Mg 2 þ -ATP]. On the other hand, there is no
substitute for actually measuring the concentration when possible to
avoid imperfections in the calculations and also systematic errors ( McGuigan
et al.,2007 ).
Two commonly used programs are Chelator by Theo Schoenmakers
( Schoenmakers et al., 1992 ) and the MaxChelator series by one of the authors
(CWP). Chelator is written for DOS and has not been updated since 1992 (making
it less broadly useful in 2010) as fewer computers and users run DOS programs and
the user interface is dated. The MaxChelator series expanded into Windows (both
16 and 32 bit), and more recently into the web via Javascript to be more OS neutral.
This website has downloadable versions of the MaxChelator suite, Chelator, and
several other related tools (including the Bers' Spreadsheets as in Fig. 6 ): http://
maxchelator.stanford.edu/downloads.htm

V

1. Ideal Software Criteria

1. First and foremost is the software has to give the correct answer or at least
close enough that it does not a V ect the experimental conclusions (and allows

measurement verification).
2. Must be easy to use. Users should not be confused as to where to enter
information or what information to enter.
3. Adaptable. There should be an easy way to enter di V erent constants and

erent methods of doing some of the calculations.
4. Source code available so the knowledge is not lost with the programmer/
researchers.

possibly even allow for di V

No current software handles all these requirements well.