Table 1 Thermodynamic data for purified variants of CI2 identified with the folding sensor.

From: Synergistic stabilization of a double mutant in chymotrypsin inhibitor 2 from a library screen in E. coli

Variant

Tm (K)

ΔHm (kJ mol−1)

ΔCp (kJ mol−1 K−1)

m (kJ mol−1  M−1)

ΔGf (kJ mol−1)

[D]50% (M)

ΔΔGf (kJ mol−1)

aI30K, I57A

327.4 ± 3.1

−99 ± 11

−0.4 ± 0.8

8.8 ± 1.8

−8.2 ± 0.6

0.9 ± 0.2

 

A16D, P33Q, G35E, V38M, Q59K

333.3 ± 1.9

−134 ± 9

−2.6 ± 0.3

5.4 ± 0.5

−9.1 ± 0.6

1.7 ± 0.2

 

K18E, P33Q, V47D

336.0 ± 1.7

−147 ± 10

−2.9 ± 0.1

4.3 ± 0.2

−10.1 ± 1.0

2.3 ± 0.2

 

aI44N, I57A

339.0 ± 2.4

−163 ± 28

−2.6 ± 0.4

7.4 ± 1.5

−13.0 ± 2.8

1.8 ± 0.5

 

A27V, D52G

341.7 ± 1.0

−211 ± 19

−3.6 ± 0.3

6.0 ± 0.8

−16.4 ± 1.5

2.7 ± 0.4

 

aE41G, F50L, I57A

331.6 ± 0.5

−191 ± 3

−1.5 ± 0.1

11.5 ± 0.2

−16.6 ± 0.4

1.4 ± 0.0

 

A16T, N56I

339.4 ± 0.6

−227 ± 19

−4.1 ± 0.3

7.0 ± 0.4

−17.0 ± 1.5

2.4 ± 0.2

 

aV31D, I57A

344.7 ± 0.5

−222 ± 0

−3.7 ± 0.0

7.0 ± 0.0

−17.7 ± 0.1

2.5 ± 0.0

 

aI57A

333.1 ± 0.5

−269 ± 14

−5.4 ± 0.5

11.6 ± 0.6

−17.9 ± 0.6

1.5 ± 0.1

 

G10E, T39S

339.7 ± 0.7

−238 ± 16

−4.0 ± 0.7

8.5 ± 0.5

−18.4 ± 0.4

2.2 ± 0.1

 

aM40T, R48S, I57V

344.3 ± 0.3

−235 ± 9

−3.8 ± 0.2

7.1 ± 0.1

−19.1 ± 0.4

2.7 ± 0.1

 

G35W, A58V

336.8 ± 0.1

−281 ± 19

−5.7 ± 0.5

6.9 ± 0.2

−19.1 ± 0.9

2.8 ± 0.1

 

E4G

341.5 ± 0.1

−259 ± 7

−4.0 ± 0.2

7.3 ± 0.1

−21.4 ± 0.3

2.9 ± 0.1

 

L32Q, I57S

348.1 ± 0.6

−275 ± 5

−4.4 ± 0.0

6.1 ± 0.2

−22.9 ± 0.7

3.8 ± 0.2

 

V13E

343.1 ± 0.2

−280 ± 23

−4.1 ± 0.5

9.6 ± 0.6

−24.0 ± 1.6

2.5 ± 0.2

 

aE15G, M40T, R48C, I57V

347.6 ± 0.1

−281 ± 8

−4.1 ± 0.1

8.3 ± 0.2

−24.9 ± 0.7

3.0 ± 0.1

 

aV38E, I57V

348.8 ± 0.3

−295 ± 16

−4.4 ± 0.3

8.9 ± 0.5

−25.8 ± 1.2

2.9 ± 0.2

 

T39A, I57N

343.5 ± 0.2

−312 ± 0

−4.7 ± 0.0

10.6 ± 0.1

−26.4 ± 0.1

2.5 ± 0.0

 

L49I

350.3 ± 0.2

−322 ± 8

−4.6 ± 0.1

8.7 ± 0.2

−28.9 ± 0.8

3.3 ± 0.1

3.4 ± 0.1

V34E, D45Y

344.3 ± 0.0

−363 ± 7

−6.0 ± 0.2

8.4 ± 0.2

−29.2 ± 0.5

3.5 ± 0.1

 

wild-type

352.3 ± 0.2

−322 ± 11

−4.3 ± 0.2

8.2 ± 0.1

−30.5 ± 0.8

3.7 ± 0.1

0

P33L

354.1 ± 0.5

−330 ± 43

−4.2 ± 0.7

8.3 ± 0.8

−32.5 ± 3.5

3.9 ± 0.6

 

aL49I, I57V

356.2 ± 0.3

−332 ± 13

−4.2 ± 0.2

7.9 ± 0.4

−32.9 ± 1.3

4.2 ± 0.3

−3.8 ± 0.1

aI57V

354.5 ± 0.2

−349 ± 12

−4.7 ± 0.2

8.3 ± 0.2

−33.3 ± 0.9

4.0 ± 0.1

−2.2 ± 0.1

aD55G, I57V

361.6 ± 0.3

−364 ± 13

−4.3 ± 0.2

8.5 ± 0.2

−38.1 ± 0.8

4.5 ± 0.1

−6.5 ± 0.2

D55G

361.1 ± 0.1

−378 ± 10

−4.7 ± 0.1

8.5 ± 0.2

−38.4 ± 1.0

4.5 ± 0.2

−6.9 ± 0.3

  1. aVariant selected from the I57A library.
  2. Tm, is the melting temperature in the absence of denaturant. ΔHm is the enthalpy change for folding at Tm. ΔCp is the change in heat capacity for folding. m is the m-value for GuHCl unfolding. ΔGf is the free energy for folding at 298 K. [D]50% is the midpoint for the GuHCl unfolding at 298 K and ΔΔGf is the change in stability at 298 K relative to wild-type from a fit of six variants with a common m-value of 8.4 ± 0.3 kJ mol−1 M−1. The errors are the propagated standard errors from the global fits of the data.
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