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Table 2 Results from peptide binding studies

From: Molecular insights into substrate recognition and catalytic mechanism of the chaperone and FKBP peptidyl-prolyl isomerase SlyD

Construct

Peptide

N1

KD1 μM

ΔH1 (kcal/mol)

–T · ΔS1 (kcal/mol)

N2

KD2 μM

ΔH2 (kcal/mol)

–T · ΔS2 (kcal/mol)

Comments

TtSlyDFL

S2

0.92 ± 0.02

0.161 ± 0.020

–15.8 ± 0.11

6.6

1.00 ± 0.01

2.97 ± 0.22

–9.4 ± 0.36

1.8

25 °C

S2

0.88 ± 0.02

0.128 ± 0.013

–16.6 ± 0.10

6.1

0.92 ± 0.01

2.23 ± 0.15

–10.5 ± 0.50

2.9

25 °C, tag-free

S2

0.98 ± 0.01

0.150 ± 0.021

–14.8 ± 0.11

5.5

1.05 ± 0.01

3.16 ± 0.18

–8.9 ± 0.25

1.4

25 °C, 5 % DMSO

S2

0.96 ± 0.03

0.113 ± 0.012

–10.0 ± 0.11

0.7

0.96 ± 0.02

2.93 ± 0.12

–4.9 ± 0.22

–2.5

20 °C

S3

0.89 ± 0.07

0.869 ± 0.156

–9.1 ± 0.05

0.8

0.86 ± 0.04

22.94 ± 1.27

–9.8 ± 0.39

3.5

25 °C

T1

    

1.13 ± 0.05

158 ± 19

–14.6 ± 0.80

9.5

25 °C

SlpA linker

    

1.44 ± 0.08

133 ± 23

–0.4 ± 0.05

–4.9

25 °C

S2-minus1

0.89 ± 0.02

0.667 ± 0.059

–16.6 ± 0.12

8.2

0.82 ± 0.02

7.25 ± 0.15

–11.1 ± 0.29

4.1

25 °C

S2-minus2

0.96 ± 0.03

1.472 ± 0.133

–16.1 ± 0.21

8.1

0.99 ± 0.06

14.77 ± 1.09

–4.3 ± 0.92

–2.3

25 °C

S2-minus3

0.94 ± 0.06

2.383 ± 0.321

–17.0 ± 0.73

9.4

1.17 ± 0.06

9.35 ± 0.49

–2.1 ± 1.41

–4.8

25 °C

S2-plus1

1.06 ± 0.03

0.317 ± 0.037

–11.4 ± 0.13

2.3

0.94 ± 0.03

3.28 ± 0.08

–7.8 ± 0.23

0.4

25 °C

S2-plus2

0.88 ± 0.02

0.183 ± 0.018

–13.1 ± 0.14

3.9

0.75 ± 0.04

5.68 ± 0.27

–8.4 ± 0.39

1.2

25 °C

S2-long2

0.72 ± 0.01

0.077 ± 0.007

–10.8 ± 0.05

1.2

1.00 ± 0.01

6.62 ± 0.39

–5.5 ± 0.14

–1.4

20 °C

S2-long4

0.74 ± 0.01

0.070 ± 0.004

–11.1 ± 0.04

1.5

0.87 ± 0.01

4.16 ± 0.20

–5.3 ± 0.10

–1.9

20 °C

S2-long6

0.74 ± 0.01

0.035 ± 0.003

–10.5 ± 0.04

0.6

0.89 ± 0.01

4.52 ± 0.32

–4.7 ± 0.11

–2.5

20 °C

S2-long8

0.95 ± 0.01

0.052 ± 0.006

–11.7 ± 0.03

1.9

0.71 ± 0.02

7.93 ± 0.46

–6.9 ± 0.22

–0.1

20 °C

S2-short2

0.72 ± 0.03

0.232 ± 0.043

–9.7 ± 0.21

0.9

0.91 ± 0.02

3.16 ± 0.24

–5.5 ± 0.34

–1.9

20 °C

S2-short4

0.73 ± 0.24

1.193 ± 0.666

–10.7 ± 2.33

2.7

0.87 ± 0.23

4.24 ± 0.50

–6.3 ± 3.02

–0.9

20 °C

S2-short6

    

1.80 ± 0.01

21.93 ± 0.51

–5.4 ± 0.04

–0.8

20 °C

S2-short8

    

1.29 ± 0.30

163.4 ± 26.4

–5.1 ± 1.54

–0.1

20 °C

S2-P25A

0.92 ± 0.01

0.129 ± 0.028

–16.6 ± 0.16

7.2

1.02 ± 0.04

7.04 ± 1.27

–8.5 ± 0.82

1.5

25 °C

S2-P29E

0.88 ± 0.02

0.513 ± 0.052

–15.8 ± 0.16

7.2

1.02 ± 0.04

5.68 ± 0.57

–2.7 ± 0.48

–4.5

25 °C

S2-P25A/P29E

1.13 ± 0.03

1.447 ± 0.295

–14.1 ± 0.33

6.1

1.09 ± 0.24

44.05 ± 8.42

–5.9 ± 1.91

–0.1

25 °C, 5 % DMSO

S2-P25N/P29N

0.93 ± 0.02

0.234 ± 0.043

–16.8 ± 0.12

7.8

1.18 ± 0.18

8.33 ± 1.54

–2.3 ± 0.33

–4.4

25 °C, 5 % DMSO

SlpA linker P5T

    

1.76 ± 0.12

130 ± 20

–0.9 ± 0.10

–4.4

25 °C

S2-W23A

0.76 ± 0.03

0.855 ± 0.332

–15.8 ± 0.24

7.5

0.91 ± 0.40

18.83 ± 6.2

–2.3 ± 0.97

–4.2

25 °C

TtSlyDΔIF

S2

    

0.91 ± 0.01

14.43 ± 0.46

–10.0 ± 0.07

3.4

25 °C

S2

    

0.88 ± 0.02

12.23 ± 0.24

–5.9 ± 0.11

0.4

20 °C

S3

    

0.89 ± 0.07

34.25 ± 3.40

–10.5 ± 1.02

4.4

25 °C

S2-P25A

    

0.91 ± 0.01

12.13 ± 0.76

–11.7 ± 0.24

5.0

25 °C

S2-P29E

    

0.69 ± 0.03

13.81 ± 0.88

–10.8 ± 0.27

4.2

25 °C

S2-P25A/P29E

    

0.84 ± 0.06

28.98 ± 4.62

–6.3 ± 0.58

0.1

25 °C, 5 % DMSO

S2-W23A

    

0.77 ± 0.02

17.06 ± 1.13

–8.1 ± 0.25

1.6

25 °C

  1. In most cases, the Isothermal titration calorimetry data clearly supported the presence of two binding sites. Where data could be described by only a single binding site, the results are given in the columns for binding site 2. Note that the binding experiments with the proline double mutant peptides were carried out in 5 % dimethyl sulfoxide (DMSO) due to solubility issues. However, this is not expected to appreciably affect the experiments, as the S2 peptide was found to bind with similar affinities in both the presence and absence of 5 % DMSO
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