Table 1.
xu, ku, ΔGu‡, and K of Structural Segments of Bovine Rhodopsina
| secondary structure |
structural segment |
xu (±SD) (nm) |
ku (±SD) (s−1) |
ΔGu‡ (kBT) | K (N/m) |
|---|---|---|---|---|---|
| N-terminal region | N1 | 0.29 ± 0.06 | (4.1 ± 7.5) × 10−1 | 22 | 2.1 |
| N-terminal region | N2 | 0.21 ± 0.03 | 1.7 ± 1.6 | 20 | 3.8 |
| α-helix I | H1 | 0.24 ± 0.02 | (5.0 ± 3.7) × 10−1 | 21 | 3.0 |
| loop C-I | C1 | 0.22 ± 0.04 | 1.3 ± 1.3 | 20 | 3.5 |
| α-helix II | H2.1 | 0.25 ± 0.03 | 1.6 ± 1.2 | 20 | 2.7 |
| α-helix II | H2.2 | 0.47 ± 0.09 | (2.1 ± 4.1) × 10−2 | 25 | 0.9 |
| loop E-I | E1 | 0.33 ± 0.03 | (7.9 ± 5.9) × 10−2 | 23 | 1.8 |
| α-helices III and IV, loops C-II and E-II |
H3, H4, C2, E2 | 0.21 ± 0.02 | (14.8 ± 9.3) × 10−2 | 23 | 4.2 |
| α-helix V and loop C-III | H5, C3 | 0.25 ± 0.03 | (9.0 ± 8.2) × 10−2 | 23 | 3.0 |
| α-helix VI | H6.1 | 0.34 ± 0.05 | (1.0 ± 1.2) × 10−1 | 23 | 1.6 |
| α-helix VI | H6.2 | 0.42 ± 0.07 | (1.3 ± 1.6) × 10−1 | 23 | 1.1 |
| loop E-III | E3 | 0.34 ± 0.04 | (1.8 ± 1.6) × 10−1 | 22 | 1.6 |
| α-helix VII | H7 | 0.36 ± 0.04 | (7.4 ± 7.0) × 10−2 | 23 | 1.5 |
| α-helix 8 | H8 | 0.44 ± 0.14 | (6.6 ± 22.1) × 10−3 | 26 | 1.1 |
| C-terminal region | CT | 0.33 ± 0.06 | (4.5 ± 7.0) × 10−2 | 24 | 1.8 |
a
Values shown for parameters xu and ku, obtained from DFS experiments (Figure 1) indicate structural and energetic properties of each structural segment. Structural segment N2, segments C1 and H3, H4, C2, and E2 constitute the rigid parts of rhodopsin, and segment H2.2 and segments H6.2 and H8 constitute the flexible regions.