TABLE 3.
Determination of iron and sulfur content of purified His-tagged SP lyase
| Sample no. | Protein content (nmol)a | A593 | A670 | Fe content (nmol)b | S content (nmol)c | Iron/protein or sulfur/ pro- tein ratiod |
|---|---|---|---|---|---|---|
| Iron | ||||||
| 1 | 8.26 | 0.155 | 8.0 | 0.97 | ||
| 2 | 5.29 | 0.080 | 3.7 | 0.70 | ||
| 3 | 3.40 | 0.082 | 3.8 | 1.12 | ||
| 4 | 1.89 | 0.059 | 2.5 | 1.32 | ||
| Sulfur | ||||||
| 1 | 4.96 | 0.247 | 7.72 | 1.56 | ||
| 2 | 2.48 | 0.129 | 4.03 | 1.63 |
a
Determined by Bradford assay of protein concentration and the deduced molecular mass of the 10×His-tagged SP lyase from the E. coli overexpression system (42,353 Da).
b
A593 of 1 nmol of Fe = 0.033.
c
A670 of 1 nmol of S2− = 0.032 (28).
d
Averages ± SDs: iron/protein ratio, 1.03 ± 0.26; sulfur/protein ratio, 1.60 ± 0.05.