Table 2 Kinetic parameters (\(\mu \)M,\(\mu \)M/h,/h)

\(V_{\mathrm{AADC}}\)

Aromatic amino acid decarboxylase

\(K_m\)

160

160

[23]

\(V_{max}\)

400

*

\(V_{\mathrm{CATAB}}\)

Catabolism of serotonin

\(K_m\)

95

94–95

[24, 25]

\(V_{max}\)

4000

*

\(V_{\mathrm{DRR}}\)

Dihydropteridine reductase

\(K_{bh2}\)

100

4–754

[26, 27]

\(K_{\mathrm{NADPH}}\)

75

29–770

[28,29,30]

\(V_{max}^f\)

5000

*

\(K_{bh4}\)

10

1.1–17

[29, 31]

\(K_{\mathrm{NADP}} \)

75

29–770

[28,29,30]

\({V_{max}}^b\)

3

*

\(V_{\mathrm{MAT}}\)

Vesicular monoamine transporter

\(K_m\)

.2

.123–.253

[32, 33]

\(V_{max}\)

1230

*

\(V_{\mathrm{POOL}}\)

Linear exchange between trp and pool

\( k_{topool}\)

9

*

\(k_{frompool} \)

0.6

*

\(V_{\mathrm{SERT}}\)

Serotonin transporter

\(K_m\)

.06

0.05–1

[34]

\(V_{max}\)

250

*

\(V_{\mathrm{TPH}}\)

Tryptophan hydroxylase

\(K_{trp}\)

40

40

[35]

\( K_{bh4}\)

20

20

[35]

\(V_{max} \)

278

*

\(K_i\) (substrate inhibition)

1000

970

[35]

\(V_{trpin}\)

Neutral amino acid transporter

\(K_m\)

330

64

[36]

\( V_{max}\)

700

*

\(V_{\mathrm{U2}}\)

\(K_m\)

.17

0.17

[37, 38]

\(V_{max}\)

14

[37, 38]

Linear diffusion or catabolism

\(k^{catab}_{trp}\)

2

*

\(k^{leak}_{cht}\)

1

*

\(k_{ght}^{leak}\)

1

*

\(k^{catab}_{hiaa}\)

1

.82

[39]

\(k^{catab}_{pool}\)

1

*

\(k_{eht}^{rem}\)

40

*

The serotonin autoreceptor

\(G_{ht}^{tot}\)

10

*

\(T_{ht}^{tot}\)

10

*

\(B_{ht}^{tot}\)

10

*

\(k_1\)

20

*

\(k_2\)

200

*

\(k_3\)

30

*

\(k_4\)

200

*

\(k_5\)

36000

*

\(k_6\)

20000

*

\(\beta _1\)

1

*

\(\beta _2\)

1

*

\(\beta _3\)

1

*

The histamine \(H_3\) receptor

\(G_{ha}^{tot}\)

1

*

\(T_{ht}^{tot}\)

60

*

\(B_{ht}^{tot}\)

10

*

\(k_{7}\)

4.32

*

\(k_{8}\)

1.296

*

\( k_{9}\)

14.4

*

\( k_{10}\)

25.92

*

\( k_{11}\)

432

*

\( k_{12}\)

1440

*

Other constants (varied in some experiments)

NADP

26

*

NADPH

330

*

btrp

96

*

eha

1.39

*