STUDY OF TRYPTOPHAN REPRESSOR DYNAMICS IN SOLUTION BY NONSELECTIVE PROTON RELAXATION

The temperature dependences of proton longitudinal and transverse rela xation times were determined for the tryptophan repressor apo and hole forms in heavy water solution at resonance frequencies of 10.8, 27, a nd 100 MHz usingo our earlier model which describes protein dynamics i n solution, i.e., internal fluctuations, Brownian movement of the whol e protein, and the slowest movement caused by interprotein electrostat ic interaction. The amplitude and frequency characteristics were deter mined for all these types of movement. The NMR relaxation data were co mpared for the tryptophan repressor, lysozyme, and ribonuclease. The N MR relaxation and hydrogen exchange data were compared for the tryptop han repressor apo and hole forms. The importance of different types of internal movements for protein functioning is discussed.