INVITROGEN/MOLECULAR PROBES CONSTANTS?
CALCIUM
See: http://probes.invitrogen.com/handbook/sections/1900.html
They have been adapted to the MAXC
format assuming that, being derived from BAPTA, the hydrogen disassociation
constants are the same (admittedly a "wild" assumption, but we have to start
somewhere?).
SPECIAL NOTE FROM DONALD BERS [4/28/1999]:
"My only concern is with
the exact values of some of the fluorescent indicator Kd values. Most of these
Ca indicators have a higher Kd in the cellular environment than in a cuvette
with simple salt solutions. This is at least partly due to binding to cellular
proteins (e.g. Hove-Madsen & Bers Biophys J 63:89-97, 1992). Typically,
this increases Kd by 2-4 fold so we get Kd for indo-1 of 844-1000 nM (Bassani
et al, Biophys J 68:1453-1460, 1995) and for Fluo3 we use 1-1.1 uM (based on
work of Harkins et al BJ 65:865-881, 1993)."
Here are the Kds in order of decreasing
Ca affinity:
CHELATOR/INDICATOR |
Kd (nM) |
MAXC CONSTANT |
Intracellular
Constant
as per above |
BAPTA |
136 |
6.970 |
|
Fura Red |
140 |
6.957 |
|
Fura 2 |
145 |
6.942 |
|
Oregon Green
488 |
170 |
6.873 |
|
Calcium Orange |
185 |
6.836 |
|
Calcium Crimson |
185 |
6.836 |
|
Calcium Green-1 |
190 |
6.824 |
|
Indo-1 |
230 |
6.742 |
6.103 - 6.177 |
Fluo-4 |
345 |
6.565 |
|
Bis-fura |
370 |
6.535 |
|
Texas Red-Calcium
Green |
370 |
6.535 |
|
Fluo-3 |
390 |
6.513 |
6.062 - 6.103 |
Caclium Green-2 |
550 |
6.363 |
|
Rhod-2 |
570 |
6.348 |
|
Oregon Green
488-BAPTA-2 |
580 |
6.340 |
|
X-rhod-1 |
700 |
6.258 |
|
The rest of the MAXC constants for
BAPTA are: [Fura and related compouinds have only (3) H constants, so only use
H1, H2 and H3, leaving H4 at ZERO, check Molecular Probes handbook for individual
formulas]
H1 |
H2 |
H3 |
H4 |
6.360 |
5.470 |
1.000 |
1.000 |
|
|
|
|
dH1 |
dH2 |
dH3 |
dH4 |
0.01 |
0.01 |
0.00 |
0.00 |
The Ca-BAPTA constants are:
CaM |
CaHM |
6.970 |
0.000 |
|
|
dCaM |
dCaHM |
4.70 |
0.00 |
If anyone has more precise values
for any of the above, please let me know, cpatton@stanford.edu
These values are more likely to be
valid the closer they are to the experimental conditions that Molecular Probes
used to assess the Kd in the first place, 22C, pH 7.2, 0.110N