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 |
|
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