Table 5.
Enzyme | Exchanges | SPDS activity | PMT activity | ||
---|---|---|---|---|---|
vmax [pkat mg−1] | vmax [pkat mg−1] | Km putrescine [μM] Km SAM [μM] | kcat [1 s−1] | ||
AtSPDS1 wild type | – | 20,722 ± 351.1 | – | 220 ± 18.44 | 0.722 |
18 ± 1.23 (dcSAM) | |||||
AtSPDS1 mutant | D131I | 29 ± 0.74 | 119 ± 2.74 | 56 ± 4.45 | 4.48 × 10−3 |
28 ± 0.77 | |||||
D131I, | 6 ± 0.33 | 100 ± 0.75 | 126 ± 9.22 | 3.80 × 10−3 | |
Q107T | 38 ± 1.43 | ||||
D131I, | 14 ± 1.28 | 250 ± 2.18 | 85 ± 5.24 | 9.51 × 10−3 | |
V134T | 65 ± 2.54 | ||||
D131I, | 4 ± 0.58 | 2155 ± 17.55 | 32 ± 1.88 | 0.081 | |
Q107T, | 12 ± 0.60 | ||||
V134T | |||||
D131I, | <d.l. | 144 ± 1.61 | 100 ± 7.67 | 5.47 × 10−3 | |
Q107T, | 50 ± 2.65 | ||||
V134T, | |||||
L98H |
<d.l., below detection limit; n.d., not determined; n = 3–4 ± standard error.