Electron spin labeling reveals the highly dynamic N-terminal arms of the SOS mutagenesis protein UmuD.

Electron paramagnetic resonance (EPR) spectroscopy was used to probe the conformational dynamics of the N-terminal arms of the umuD gene products. We determined that the arms of UmuD(2) display a large degree of motion, are largely unbound from the globular C-terminal domain, and that the free energy of dissociation is +2.1 kJ mol(-1).