Table 1. Expected and observed monoisotopic masses (MH+) of tryptic fragments from NEM-reacted mitochondrial Trx 2.
Trx 2 (100 μM) was reduced with TCEP, treated with NEM (Trx 2 to NEM; 1:5), digested with trypsin, and analyzed by MALDI-TOF. The amino acid sequences of the tryptic fragments are indicated (T1 - T12). T2 is the Cys-containing fragment. NEM-modified fragments by one addition (−NEM) or two additions (− 2NEM) of NEM are indicated.
| Fragment | Expected mass (MH+) | Observed mass (MH+) |
|---|---|---|
| Cys-containing peptides | ||
| T2 dithiols (Cys 90, Cys93) | 2315.09 | 2315.15 |
| T2-1NEM | 2440.09 | 2440.2 |
| T2-2NEM | 2565.09 | ND |
|
| ||
| Other identified peptides | ||
| T1 | 1653.75 | 1653.80 |
| T8 | 2744.36 | 2745.45 |
|
| ||
| Amino acid sequences of the Trx2 tryptic fragments | ||
| 60 TTFNIQDGPDFQDR(T1), VVNSET PVVVDFHAQWCGPCK(T2), 95 ILGPR(T3), LEK(T4), MVAK(T5), QHG K(T6),VVMAK(T7), 116 VDIDDHTDLAIEYEVSAVPTVLAMK(T8), NGDVVDK(T9), 149 FVGIK(T10), DEDQLEAFLKK(T11), LIG(T12) | ||
| The mitochondrial localization signal from 1 to 59, which is removed upon mitochondrial import, is not shown. | ||