Table 2. Orbitrap MS/MS Analysis of Modified Peptides Derived from GlgE after Exposure to 2-Deoxy-2-fluoro-α-maltosyl Fluoride.
| E423A S. coelicolor GlgE | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| R392a | V | D*b | N | P | H | T | K | P | V | A | F403 | |
| b-ions | 157.10 | 256.17 | 697.30 | 811.34 | 908.40 | 1045.45 | 1146.50 | 1274.60 | 1371.65 | 1470.72 | 1541.76 | – |
| y-ions | – | 1550.73 | 1451.67 | 1010.54 | 896.49 | 779.44 | 662.38 | 561.33 | 433.24 | 336.19 | 237.12 | 166.08 |
| M. tuberculosis GlgE | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| F415a | R | V | D*b | N | P | H | T | K | P | P | N | F427 | |
| b-ions | 148.07 | 304.17 | 403.24 | 844.37 | 958.41 | 1055.46 | 1192.52 | 1293.57 | 1421.67 | 1518.72 | 1615.77 | 1729.81 | – |
| y-ions | – | 1747.82 | 1591.72 | 1492.66 | 1051.53 | 937.48 | 840.43 | 703.37 | 602.32 | 474.23 | 377.18 | 280.12 | 166.08 |
a
The peptide was sequenced by assignment of the m/z of singly charged b-ions and y-ions.
b
D* denotes the modified residue with an observed mass change within the b-ion series of 441.13 Da in both cases that was consistent with the predicted value (115.03 Da for the Asp plus 326.10 Da for the 2-deoxy-2-fluoromaltosyl group, giving 441.16 Da).