Pressure-induced changes in the secondary structure of the Escherichia coli methionine repressor protein.

The effect of hydrostatic pressure on the conformational properties of the E. coli methionine repressor protein in aqueous solution was investigated by infrared spectroscopy. Changes in hydrostatic pressure produce dramatic changes in the spectral region of the conformation-sensitive amide I band. As the pressure is raised up to 18 kbar, the protein undergoes a rearrangement of alpha-helical segments into beta-type structures; after the pressure is released the beta-strands reconvert into less ordered alpha-helical or random segments.