Table I.
Confirmation of N-terminal semi-tryptic peptides by MS/MS
Daughter ions (b ions) observed from MS/MS spectra of the three N-terminal semi-tryptic peptides (I, II, and III) derived from the 33-kD protein band (see Fig. 4). A full set of y-ions was also observed for peptides I and II, but not for III, probably due to the low parent ion intensity.
| Daughters | Ion | m/z Observed | MH+ Calc. | Δ |
|---|---|---|---|---|
| mD | ||||
| (I) 904.527 ATLPVFTR | ||||
| ATLPVFTR | b8 | 904.529 | 904.526 | 3 |
| ATLPVFT | b7-18 | 712.416 | 712.404 | 12 |
| ATLPVF | b6 | 629.371 | 629.366 | 5 |
| ATLPV | b5 | 482.299 | 482.298 | 1 |
| ATLP | b4 | 383.228 | 383.230 | −2 |
| ATL | b3 | 286.177 | 286.177 | 0 |
| AT | b2 | 173.090 | 173.093 | −3 |
| (II) 1,005.571 TATLPVFTR | ||||
| TATLPVFTR | b9 | 1,005.580 | 1,005.573 | 7 |
| TATLPVFT | b8-18 | 813.453 | 813.451 | 2 |
| TATLPVF | b7-18 | 712.401 | 712.404 | −3 |
| TATLPV | b6-18 | 565.327 | 565.335 | −8 |
| TATLP | b5 | 484.283 | 484.277 | 6 |
| TATL | b4-18 | 369.215 | 369.214 | 1 |
| TAT | b3-18 | 256.129 | 256.130 | −1 |
| TA | b2 | 173.098 | 173.093 | 5 |
| (III) 1,076.614 ATATLPVFTR | ||||
| ATATLPVFTR | b10 | 1,076.616 | 1,076.610 | 6 |
| ATATLPVF | b8 | 801.449 | 801.451 | −2 |
| ATATLP | b6-18 | 537.312 | 537.304 | 8 |
| ATATL | b5-18 | 440.249 | 440.251 | −2 |
| ATAT | b4-18 | 327.175 | 327.167 | 8 |
| ATA | b3-18 | 226.123 | 226.120 | 3 |
| AT | b2 | 173.093 | 173.093 | 0 |