Electrophoresis at elevated hydrostatic pressure of the multiheme hydroxylamine oxidoreductase

The behavior of the multiheme protein hydroxylamine oxidoreductase (HAO) in polyacrylamide gel electrophoresis was studied at hydrostatic pressures up to 3 kbar at 25 degrees C. Due to the limited working volume of the high pressure vessel, the electrophoresis cells were miniaturized. A microcell which accommodates 6 capillary gel tubes is described. Between 1 bar and 1.5 kbar the enzyme did not undergo structural changes detectable in the gel system. At approximately 2 kbar the active form of the enzyme was partially dissociated. At higher pressures, the enzyme was converted to forms which were irreversibly inactive and had a higher apparent molecular mass, suggesting aggregation or denaturation.