Biology Reference
In-Depth Information
A
6
5
Data
Prediction
4
3
2
1
8
15
22
29
36
Temperature (
C)
B
8
7
6
5
4
Data
3
Prediction
2
1
0
0.1
0.15
0.2
0.25
0.3
Ionic strength (M)
Fig. 5
The e
V
ect of temperature (A) and ionic strength (B) on the apparent Ca
2
þ
a
Y
nity (K
0
Ca
)ofBr
2
-
BAPTA. The experimental data is from
Harrison and Bers (1987)
at pH 7.00 and 0.19 M ionic strength
(A) and at pH 7.00 and 22
C (B). Predicted values are based on the temperature and ionic strength
corrections described in the text.
where R is the Ca
2
þ
bu
er. This expression is not too useful directly, because we do
not know any of the variables on the right side. It is generally more useful to have
[Ca
2
þ
] or bound Ca
2
þ
([CaR]) in terms of known quantities, like total Ca
2
þ
([Ca
t
])
or total chelator ([R
t
]). One of the complicating factors is also that Ca
2
þ
bu
V
V
ers
like EGTA or BAPTA exist in multiple unbound forms in di
V
erent states of
protonation. Then for a tetravalent Ca
2
þ
bu
V
er like EGTA, the total of the non-
Ca
2
þ
bound forms of the bu
V
er is
R
½
¼½
þ½
þ½
þ½
þ½
ð2Þ
CaR
R
HR
H
2
R
H
3
R
H
4
R
