Table 2. Summary of H/D exchange data for the PKA catalytic subunit.
| Deuteration after 10 min
|
||||
|---|---|---|---|---|
| Sequence of PKA C-subunit (m/z) | Number of amides | C-subunit (+Mg2+, ATP) | Holoenzyme RIα(94—244)-C | Holoenzyme (RIα)2C2 |
| 18—26 (1,068.57) | 8 | 7.16 | 6.22±0.09 | ND |
| 44—54 (1,194.65) | 10 | 6.84±0.11 | 3.54±0.29 | 3.64±0.06 |
| 43—54 (1,341.72) | 11 | 7.26±0.19 | 4.11±0.01 | ND |
| 41—54 (1,584.8) | 13 | 9.11±0.45 | 6.15±0.18 | 6.01±0.02 |
| 66—83 (2,113.2323)* | 17 | 1.69±0.01 | 1.55±0.04 | ND |
| 92—100 (1,088.66) | 8 | 3.15±0.28 | 3.16±0.10 | 3.11±0.16 |
| 133—145 (1,628.89) | 11 | 5.75±0.01 | 3.24±0.19 | 4.83±0.05 |
| 164—172 (1,147.61) | 7 | 2.58±0.10 | 1.21±0.01 | 1.28±0.02 |
| 163—172 (1,260.69) | 8 | 2.94±0.06 | 1.11±0.14 | 1.13±0.08 |
| 212—221 (1,167.58) | 9 | 6.18±0.25 | 3.37±0.00 | 3.64±0.06 |
| 247—261 (1,793.97) | 13 | 10.32±0.15 | 7.74±0.42 | 7.53±0.02 |
| 247—264 (2,084.22) | 16 | 12.13±0.01 | 9.37±0.15 | 8.49±0.06 |
| 247—265 (2,197.33) | 17 | 12.01±0.02 | 9.58±0.05 | 8.46±0.12 |
| 268—276 (1,083.65) | 8 | 2.82±0.11 | 2.78±0.15 | ND |
| 278—289 (1,347.75) | 11 | 6.09±0.01 | 5.25±0.03 | 4.99±0.05 |
| 303—326 (2,676.45)† | 20 | 14.12±0.45 | 14.13±0.17 | 13.10±0.13 |
| 303—327 (2,823.52) | 21 | 15.00±0.43 | 14.88 | 13.77±0.25 |
ND, Not determined.
*
This row of data is from a partial centroid because of peak overlap and does not represent the absolute number of amides exchanging although relative differences can be seen
†
One additional amide is protected in C-subunit upon binding the full-length R-subunit, and this result is due to the presence of residues upstream of the pseudosubstrate sequence (30)