Table 2.
Mutants of M. extorquens PqqE studied. Each was reconstituted, assayed for SAM cleavage, Fe content and ability to form cross-linked PqqA. Assays were carried out using established procedures (Materials and Methods).
| Name | Mutations of Cys within RS and 2 Aux Sites | SAM Cleavage | Fe/Protein | Modification of PqqAa |
|---|---|---|---|---|
| WT | None | 0.031/min | 13.0 +/− 0.1 | Yes |
| −RS | C32A,C35A | None Observed | 8.7 +/− 0.8 | No |
| −AuxII | C310A,C313A | 0.0045/min | 7.3 +/− 0.6 | No |
| +RS | All to Ser except C28,32,35 | 0.00043/min | 4.6 +/− 0.7 | No |
| D319A | D319A | 0.0037/min | 8.9 +/− 0.9 | No |
a
We note the low yields for cross-linked PqqA, optimally 10% for WT enzyme: A failure to observe cross-linked product for the variants described is, thus, “within the limits of detection.”