Table 1 Enzymatic parameters of purified RhGCs and truncated cyclases

Substrate

GTP

GTP

GTP

GTP

ATP

Hill fit R²

0.98

0.99

0.96

0.98

0.97

K_M (mM)

0.92 ± 0.27

2.16 ± 0.30

6.1 ± 5.59

5.78 ± 2.04

6.09 ± 1.74

n

1 ± 0.18

1.72 ± 0.12

1.13 ± 0.42

1.22 ± 0.08

1.29 ± 0.06

v_max (cNMP (µmol min⁻¹ mg_protein⁻¹))

1.82 ± 0.19

1.89 ± 0.18

11.64 ± 5.67

6.30 ± 1.54

5.64 ± 1.24

v_max (cNMP (µmol min⁻¹ µmol_protein⁻¹))

128.5 ± 13.4

40.67 ± 3.87

821.8 ± 400.3

135.59 ± 33.14

121.38 ± 26.68

k_cat (min⁻¹)

64.3

20.34

410.9

67.80

60.69

k_cat (s⁻¹)

1.1

0.34

6.85

1.13

1.01

k_cat/K_M (s⁻¹ mM⁻¹)

1.2

0.16

1.12

0.20

0.17

Molecular weight (kDa)

70.6

21.5

70.6

21.5

21.5

Illumination

522 nm, 0.010 mW mm⁻²

522 nm, 0.010 mW mm⁻²