Table 2. Cross-Diagonal Distances (Å) between Helices A–C and B–D in the Apo Form of the wt and V27A Channelsa.
| wt |
V27A |
||||
|---|---|---|---|---|---|
| d1 | d2 | d1 | d2 | Δb | |
| Val27 | 10.3 ± 0.5 (8.3 ± 0.6) | 10.6 ± 0.5 (8.6 ± 0.6) | 11.6 ± 0.7 (10.0 ± 0.9) | 11.5 ± 0.8 (9.9 ± 0.9) | +1.1 (+1.5) |
| Ser31 | 11.0 ± 0.4 (11.2 ± 0.5) | 10.7 ± 0.4 (10.8 ± 0.5) | 11.4 ± 0.6 (12.0 ± 0.7) | 11.3 ± 0.6 (12.0 ± 0.7) | +0.5 (+1.0) |
| Gly34 | 10.1 ± 0.4 | 9.3 ± 0.5 | 9.6 ± 0.6 | 9.4 ± 0.6 | –0.2 |
| His37 | 13.4 ± 0.5 (10.6 ± 0.5) | 12.3 ± 0.8 (9.9 ± 0.9) | 12.3 ± 0.6 (9.6 ± 0.6) | 11.8 ± 0.8 (9.2 ± 0.9) | –0.8 (−1.0) |
a
Values measured from the Cα atoms of residues in the tetrad; values determined from the Cβ atoms are given in parentheses.
b
Difference between cross-diagonals in wt and V27A channels (positive values imply a widening of the pore in the V27A channel).