TABLE 3.
Release probability per path for the wild-type pre-powerstroke myosin and eight single-point alanine mutants. The results were obtained from a series of MCES simulations in the pre-release temperature range for the wild-type, i.e., at a ligand temperature of 1500 K. The data indicate that residues R238 and E459, which form the salt-bridge crucial for hydrolysis [39], make the largest contribution to the release barrier along the backdoor I path. Alanine substitutions of S181, T230, and R232 slightly increase the release probability but favor side-door release.
| Protein sequence | Exit path (%) | |||||
|---|---|---|---|---|---|---|
| back I | back II | side | front | rear | top | |
| wt | x | x | 1.0 | x | 0.2 | 0.1 |
| S181A | 3.7 | x | 7.5 | 0.2 | 0.5 | 0.2 |
| T230A | x | x | 2.8 | x | x | x |
| R232A | 2.3 | x | 8.8 | x | 0.3 | x |
| R238A | 38.5 | x | 2.8 | x | x | 0.3 |
| E459A | 23.7 | x | 1.3 | x | x | x |
| R267A | 2.7 | x | x | x | x | x |
| F461A | 5.3 | x | 1.3 | x | x | x |
| Q468A | 4.0 | x | 2.5 | x | x | x |
| wt (2000 K) | 11.9 | x | 1.9 | 0.1 | 0.3 | x |