A short while ago I posted a question to the net regarding the use of
Ca/EGTA buffers, and more specifically whether there were any PD
programs available to calculate free Ca concentrations in such systems.
This is a summary of the replies.
1. Gregg Cohen suggested adding EGTA then dialyzing the enzyme to remove
all the Ca, then adding back Ca.
2. David Lapointe sent a listing of his program, COMICS (Perrin + Sayce,
Talanta, 14, 833, written in C which compiles with TurboC(++), for the PC.
He can be reached on lapointe at edu.uthsega.thorin.
3. Jochem Kleinschmidt described his MSDOS program, CABUFFER, which he
3. Jochem Kleinschmidt described his MSDOS program CABUFFER which he
recently sent a msg to the net about. Available by anonymous ftp
from mcclb0.med.nyu.edu (22.214.171.124). More details in his recent
4. Jim Gabern sent me by e-mail a program, Free Ca, written by a student
of Claude Klee, NIH. This is available, he says, from ftp.embl-heidelberg.
de. Be warned, this is a slow process from this site. This is the
program I used. It will calculate free Ca given EGTA, EDTA, ATP, Na,
K, phosphocreatine total concentrations, and also allows you to enter
new ligands, provided you have the stability constants. Oh, and it
obviously allows for pH.
5. Ron Grunwald mentioned a program by Fabiato described in Methods in
Enzymol. 157, 378 (1988) and CHELATOR, by Schoemaker described
in BioTechniques 12, 870 (1992).
Thanks to everyone who replied, as I said it shows the usefulness of
this net, so thanks also to those who run it.
Fergus Doherty, Biochemistry, Nottingham University, UK>