Table 4.
Estimates of malate IC 50 values for half-maximum inhibition of PEPC activity at pH 7.6 (PEP concentration, 2× the K m) in representative photosynthetic types in subfamily Suaedoideae
The amino acid residues potentially involved in malate tolerance are presented. For species comparisons, different letters indicate a significant difference within a category of G6P (+ or –) while comparison of G6P levels within a species is indicated by an asterisk (*) for significance at the P <0.05 level.
| Species | Photosynthetic | Residue at | Residue at | Residue at | Residue at | IC 50 (mM) | IC 50 (mM) | Significant |
|---|---|---|---|---|---|---|---|---|
| mode | 780 | 868 | 879 | 890 | No G6P | 5mM G6P | effect of G6P | |
| S. accuminata | Schoberia Kranz C4 | S | R | D | R | 0.6 c | 1.4 c | * |
| S. eltonica | Schoberia Kranz C4 | S | R | D | R | 1.0 b | 1.9 b | * |
| S. moquinii | Salsina Kranz C4 | A | L | N | M | 4.5 a | 5.9 a | – |
| S. fruticosa | Salsina Kranz C4 | A | L | N | M | 4.5 a | 5.2 a | – |
| S. aralocaspica | Single Cell-C4 | A | Q | E | R | 0.9 b | 1.6 bc | * |
| S. physophora | C3 | A | K | D | R | 0.3 d | 0.9 d | * |
| S. linifolia | C3 | A | K | D | R | 0.3 d | 0.8 d | * |