Calculation of Cys 30 delta pKa's and oxidising power for DsbA mutants

DsbA possesses a redox active disulphide, with the equilibrium strongly shifted towards the reduced form as compared to its structural homologue, thioredoxin. It is widely believed that the two amino acids that separate the active site cysteines play a crucial role in determining oxidising power within the thioredoxin family. Data concerning redox and pKa properties for DsbA mutants in this region are available. Electrostatics calculations show reasonable agreement with the experimental data, and support the suggestion that amino acids outside of the CXXC active site sequence are as important in determining oxidising power within the thioredoxin family as are those within it.