Table 1 Catalytic parameters (±s.e.m.) for the dehydration of L-Ser and D-Ser and racemisation of L-Ser by hSR, Q89M-hSR and Q89A-hSR.
From: Glutamine 89 is a key residue in the allosteric modulation of human serine racemase activity by ATP
Reaction | Protein | Km (mM) | kcat (min−1) | kcat/Km (s−1·M−1) | Increase | |||
|---|---|---|---|---|---|---|---|---|
−ATP | +ATP | −ATP | +ATP | −ATP | +ATP | |||
L-Ser racemisation | hSR | 35 ± 4 | 34 ± 5 | 19 ± 1 | 35 ± 1 | 9.2 ± 1.0 | 17.5 ± 2.4 | 1.9 |
Q89M-hSR | 24 ± 2 | 22 ± 2 | 14 ± 1 | 24 ± 1 | 9.9 ± 0.8 | 18.0 ± 2.0 | 1.8 | |
Q89A-hSR | 20 ± 2 | 16 ± 1 | 11 ± 1 | 14 ± 1 | 9.4 ± 0.8 | 14.7 ± 0.9 | 1.6 | |
L-Ser dehydration | hSR | 76 ± 10 | 12 ± 1 | 37 ± 4 | 183 ± 3 | 8.1 ± 1.3 | 253.0 ± 19.6 | 31 |
Q89M-hSR | 22 ± 1 | 19 ± 2 | 17 ± 1 | 56 ± 1 | 12.7 ± 0.6 | 48.9 ± 4.5 | 3.9 | |
Q89A-hSR | 28 ± 2 | 27 ± 3 | 31 ± 1 | 98 ± 1 | 18.1 ± 0.6 | 59.4 ± 3.6 | 3.3 | |
D-Ser dehydration | hSR | 46 ± 3 | 167 ± 16 | 1.7 ± 0.1 | 23 ± 1 | 0.6 ± 0.1 | 2.4 ± 0.2 | 4.0 |
Q89M-hSR | 60 ± 2 | 65 ± 7 | 3.2 ± 0.1 | 9.6 ± 0.3 | 0.9 ± 0.1 | 2.5 ± 0.4 | 2.8 | |
Q89A-hSR | n.d. | n.d. | n.d. | n.d. | 1.6 ± 0.2 | 3.6 ± 0.3 | 2.3 | |
