Table 2 Thermodynamic parameters of the binding of AbnA and its variants to branched and linear arabinan.

From: Integrative structure determination reveals functional global flexibility for an ultra-multimodular arabinanase

AbnA variant

KB × 105 (M−1)

KD (1/KB) (µM)

ΔHB [kcal/mol]

TΔSB [kcal/mol]

ΔGB [kcal/mol]

Calculated effective binding units of arabinosea

Sugar-beet arabinan

Domains1234

2.3 ± 0.3

4.3 ± 0.6

−26.1 ± 0.5

−18.7 ± 0.5

−7.43 ± 0.08

25

Domains123

1.8 ± 0.3

5.5 ± 0.9

−8.6 ± 0.2

−1.3 ± 0.2

−7.28 ± 0.10

14

Domains12

3.6 ± 0.6

2.8 ± 0.5

−15.3 ± 0.2

−7.6 ± 0.2

−7.69 ± 0.10

23

Domain4

1.3 ± 0.1

7.7 ± 0.6

−17.7 ± 0.2

−10.6 ± 0.2

−7.08 ± 0.05

11

Domains34

1.6 ± 0.1

6.2 ± 0.4

−17.5 ± 0.2

−10.3 ± 0.2

−7.21 ± 0.04

13

Linear arabinan

Domains1234

3.0 ± 0.4

3.3 ± 0.4

−31.1 ± 0.5

−23.5 ± 0.5

−7.59 ± 0.08

22

Domains123

7.1 ± 1.2

1.4 ± 0.2

−14.8 ± 0.2

−6.7 ± 0.2

−8.11 ± 0.10

13

Domains12

4.5 ± 0.6

2.2 ± 0.3

−13.5 ± 0.2

−5.7 ± 0.2

−7.83 ± 0.08

15

Domain4

0.9 ± 0.1

11.1 ± 1.2

−16.7 ± 0.3

−9.8 ± 0.3

−6.86 ± 0.07

11

  1. aTo calculate the binding constants, the molar ratio was fixed to 1, and the size of the “effective binding unit” for the polymer was calculated. The effective binding unit represents how many monosaccharide equivalents of polysaccharide chain is, on average, are required for binding (or are masked) by the protein molecule. In all the variants that include Domain1, the acid base mutant E304A was used.
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