Table 1.
The masses of the subunits of the F-ATPase from P. denitrificans and of the inhibitor protein ζ.
| subunit | observed (Da) | calculated (Da)a | Δ (Da) | modification |
|---|---|---|---|---|
| α | 54 913.0 | 54 907.9 | +5.1 | −N-fMet |
| β | 50 211.8 | 50 208.2 | +3.6 | −N-fMet |
| γ | 31 469.5 | 31 467.9 | +1.6 | −N-fMet |
| δ | 19 694.8 | 19 694.4 | 0 | Δ1–3 or Δ1–26b |
| ε | 15 692.9 | 15 692.7 | 0 | −N-fMet |
| ζ | 11 537.8 | 11 537.8 | 0 | −N-fMet |
| a | 26 593.7 | 26 592.8 | 0 | −N-fMet |
| b | 18 392.1 | 20 162.2 | −1770.1 | Δ1–17 |
| b' (3–176) | 18 454.9 | 18 454.9 | 0 | Δ1–2c |
| b' (6–178) | 18 255.7 | 18 255.7 | 0 | Δ1–5 |
| b' (7–178) | 18 140.6 | 18 140.6 | 0 | Δ1–6 |
| c | 7637.4 | 76 10.0 | +27.4 | +Nα-formyl |
aThe N-formyl methionine translational initiator is not included in these calculated values.
bThe N-terminal sequence of the δ subunit is Ala-Asn-Ser-Ala-, and the DNA sequence of the Atp operon in P. denitrificans has two possible translational initiator methionine codons in the 5′-region before the DNA sequence encoding this N-terminal sequence. Thus, the generation of the observed mature protein would require the removal of either residues 1–3 or 1–26 from the initial product of translation.
cFor a discussion of the N-terminus of subunit b’, see the text.