Table 4.
Folate pools in exponentially growing E. coli. Data are from the average of two duplicate biological extracts each analyzed four times by LC-MS/MS. Reported values are the mean peak heights. Intra-sample reproducibility (determined from the four analytical runs of the first biological replicate) and inter-sample reproducibility (determined by comparing the two biological replicates) are shown in brackets as relative standard deviation (RSD). “0” indicates that no signal was detected; “+” indicates trace signal. Note that direct comparison of the signals between different compounds is complicated by different compounds having different response factors, i.e., different species give different ion counts when present in identical concentration.
| n = | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
|---|---|---|---|---|---|---|---|---|
| pAB-Glun | 0 | + | 4541 (16%, 1%) |
0 | 0 | 0 | 0 | 0 |
| PteGlun | 0 | 0 | + | 0 | 0 | 0 | 0 | 0 |
| H2PteGlun | 0 | + | 40540 (9%, 13%) |
3250 (14%, 8%) |
1208 (41%, 7%) |
0 | 0 | 0 |
| H4PteGlun | 0 | + | 18893 (N/Aa, 3%) |
+ | 0 | 0 | 0 | 0 |
| 5,10- CH=H4PteGlun |
0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 5,10-CH2- H4PteGlun |
0 | + | 18300 (15%, 20%) |
2172 (17%, 20%) |
1312 (39%, 40%) |
0 | 0 | 0 |
| 5-CH3- H4PteGlun |
5947 (10%, 12%) |
11205 (27%, 23%) |
270889 (19%, 18%) |
40747 (8%, 4%) |
11119 (18%, 9%) |
1180 (42%, 14%) |
0 | 0 |
| 5/10-CHO- H4PteGlun |
+ | 696 (45%, 5%) |
35301 (19%, 12%) |
2106 (27%, 11%) |
+ | 0 | 0 | 0 |
H4PteGlu3 signal was found to decay monotonically following sample preparation with t1/2 ∼2 hr; therefore only results of the first analytical run on each sample, immediately following sample preparation, is reported.