TABLE 5.
Activity of the IDS-epimerase with IDS, different metal-IDS complexes, EDDS, and aspartic acid
| Substrate | Activitya (μmol of S,S-IDS/min/mg) | Relative activity |
|---|---|---|
| S,S-IDS | 46 | 100 |
| R,S-IDS | 4.88 | 9 |
| R,R-IDS | 24.5 | 53 |
| Ca2+-R,R-IDS | 24 | 52 |
| Ba2+-R,R-IDS | 20.1 | 44 |
| Mg2+-R,R-IDS | 11.3 | 25 |
| Mn2+-R,R-IDS | 1 × 10−4 | Negligible |
| Fe3+-R,R-IDS | 3 × 10−4 | Negligible |
| Fe2+-R,R-IDS | 4.2 × 10−4 | Negligible |
| Zn2+-R,R-IDS | 0 | No transformation |
| Cu2+-R,R-IDS | 0 | No transformation |
| S,S-EDDS | 0 | No transformation |
| Technical EDDS | 0 | No transformation |
| l-Aspartic acid | 0 | No transformation |
a
Enzyme assays were performed with 5 mM substrate as described in Materials and Methods. The specific activities were determined by measuring the disappearance of the substrate.