Table 1 Association constants for the interaction of E9 variants with Im2 variants determined by isothermal calorimetrya

From: Measuring inter-protein pairwise interaction energies from a single native mass spectrum by double-mutant cycle analysis

Complex

K a (μM−1)

Average valuesb

Literature values13

K a (μM−1)

K a (μM−1)

E9 wild type–Im2 wild type

1.08 (±0.09)

1.22 (±0.14)

4.83 (±0.68)

 

1.36 (±0.21)

  
 

1.23 (±0.14)

  

E9 wild type–Im2D33A

8.33 (±0.08)

13.4 ± 4.5

1.00 × 103

 

14.8 (±0.25)

  
 

17.0 (±0.21)

  

E9F86A–Im2 wild type

1.68 (±0.03) × 10−2

1.35 (±0.28) × 10−2

6.94 (±0.05) × 10−1

 

1.16(±0.02) × 10−2

  
 

1.22 (±0.02) × 10−2

  

E9F86A–Im2D33A

1.66 (±0.16)

1.61 (±0.06)

8.33 (±0.15)

 

1.63 (±0.16)

  
 

1.55 (±0.17)

  

E9 wild type–Im2N34A

1.70 (±0.12)

1.54 (±0.21)

4.34 (±0.05) × 10−1

 

1.30 (±0.12)

  
 

1.63 (±0.16)

  

E9S84A/H131A/R132A–Im2 wild type

2.34 (±0.66)

1.83 (±0.46)

N.D.

 

1.35 (±0.36)

  
 

1.37 (±0.49)

  
 

1.84 (±0.33)

  
 

2.23 (±0.31)

  

E9S84A–Im2 wild type

1.29 (±0.14)

1.41 (±0.14)

7.14 (±0.05)

 

1.36 (±0.36)

  
 

1.33 (±0.25)

  
 

1.65 (±0.43)

  
 

1.41 (±0.40)

  

E9S84A–Im2N34A

2.03 (±0.50)

2.55 (±0.49)

N.D.

 

2.53 (±0.90)

  
 

2.94 (±0.18)

  
 

3.12 (±0.38)

  
 

2.11 (±0.32)

  
  1. aA value of ~250 μM−1 was obtained for the association constant of wild-type E9 to the Im2D33A mutant when using 50 mM MOPS buffer (pH 7.0) containing 200 mM NaCl as before13. The discrepancies between the values reported here and the literature values are, therefore, most likely due to the different buffers and salt concentrations used in the two studies.
  2. bValues ± standard deviations are reported
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