# Mb binding

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```					       Oxygen Binding to myoglobin
Kd=1 Kd=5 pO2     Y for Kd=1 Y for Kd = 5                                      pO2
Kd=you choose      Y for your Kd
1    5  0.25         0.20        0.05                                           0.25       1.00
1    5    0.5        0.33        0.09                                            0.5       1.00
1    5      1        0.50        0.17                                              1       1.00
1    5      2        0.67        0.29                                              2       1.00
1    5      3        0.75        0.38                                              3       1.00
1    5      4        0.80        0.44                                              4       1.00
1    5      5        0.83        0.50                                              5       1.00
1    5      6        0.86        0.55                                              6       1.00
1    5      7        0.88        0.58                                              7       1.00
1    5      8        0.89        0.62                                              8       1.00
1    5      9        0.90        0.64                                              9       1.00
1    5     10        0.91        0.67                                             10       1.00
1    5     20        0.95        0.80                                             20       1.00
1    5     50        0.98        0.91                                             50       1.00

1. Which represents stronger binding, Kd = 5 mM or Kd=1 mM? Explain

2. How does Y change as pO2 increases?                                      Mb Saturation Curve

3. What happens to Y when Kd increases?                         1.20
1.00
4. What is special about Y = 0.5?                               0.80
0.60
Y

5. Enter your own Kd and see how it affects the binding         0.40
0.20
0.00
0                      50
pO2
Oxygen Binding to Hemoglobin

Kd mM Kd mM kd mM pO2 Y for 20 Y for 40 Y for 100
20     40    100   1    0.05    0.02       0.01
20     40    100   2    0.44    0.29       0.14
20     40    100   3    0.80    0.67       0.45                       1.20
20     40    100   4    0.93    0.86       0.72
20     40    100   5    0.97    0.94       0.86                       1.00
20     40    100   6    0.98    0.97       0.93                       0.80
20     40    100   7    0.99    0.98       0.96
0.60
20     40    100   8    1.00    0.99       0.98
20     40    100   9    1.00    0.99       0.98                       0.40
20     40    100  10    1.00    1.00       0.99                       0.20
20     40    100  20    1.00    1.00       1.00
20     40    100  40    1.00    1.00       1.00                       0.00
20     40    100  50    1.00    1.00       1.00                              0               5                10               15

1. How do these curves differ from the binding curves for myoglobin?

2. At what approximate pO 2 will the Hb be 50% saturated for Kd=20 (red), 40 (blue), and 100 (green) mM?

3. When Hb is 50% saturated, what does that mean in terms of molecular species present (i.e. 50% apo and 50% Hb(O 2 ) 4 or something else)?

4. What must be the relative values of the Kd of Mb and Hb to make sure that the transfer goes in the right direction (i.e. Hb to Mb and not the other way)? Expla
Mb and not the other way)? Explain

```
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 views: 4 posted: 8/31/2010 language: English pages: 4