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Table 1 Activation kinetics of ADP-Glc PPases from Anabaena , O. tauri , and potato tuber

From: The ancestral activation promiscuity of ADP-glucose pyrophosphorylases from oxygenic photosynthetic organisms

Enzyme

v0(U mg-1)

Activator

A0.5(mM)

Activation fold

Net activation fold

Specificity constant (mM-1)

Anabaena

0.77

3-PGA

0.075

5.5

4.5

60

  

FBP

0.30

1.2

0.2

0.7

  

Fru6P

1.6

2.5

1.5

1.0

  

Glc6P

0.40

1.4

0.4

1.0

OtaS/OtaL

0.89

3-PGA

0.54

33

32

59

  

FBP

1.1

7.0

6.0

5.5

  

Fru6P

15

2.7

1.7

0.1

  

Glc6P

75

17

16

0.2

StuS/StuL

0.27

3-PGA

0.054

68

67

1241

  

FBP

0.84

6.0

5.0

6.0

  

Fru6P

1.5

57

56

36

  

Glc6P

1.8

29

28

15

OtaS

0.25

3-PGA

1.2

10

9.0

8.0

  

FBP

1.1

9.3

8.3

7.6

  

Fru6P

1.9

3.9

2.9

1.6

  

Glc6P

10

5.5

4.5

0.4

OtaSD148A/OtaL

0.57

3-PGA

0.003

7.0

6.0

2000

  

FBP

8.2

5.0

4.0

0.5

  

Fru6P

0.74

5.0

4.0

5.4

  

Glc6P

65

26

25

0.4

OtaS/OtaLD171A

0.12

3-PGA

0.067

5.1

4.1

61

  

FBP

1.5

5.9

4.9

3.3

  

Fru6P

2.9

5.0

4.0

1.4

  

Glc6P

3.1

3.4

2.4

0.8

  1. Activity of the purified enzymes was assayed in the ADP-Glc synthesis direction. Kinetic parameters were calculated as described under “Methods”. For each enzyme and each activator the Vmax can be calculated as v0 times the Activation Fold. StuS and StuL are the S and L subunits of potato tuber, and OtaS and OtaL the S and L subunits of O. tauri, respectively.