RENATURATION OF METMYOGLOBIN SUBJECTED TO HIGH ISOSTATIC PRESSURE

Metmyoglobin solutions (0.2%) when subjected to pressures of 7.5 to 8.0 kbars at neutral pH were denatured and on standing only partially reformed the native state. The degree and rate of renaturation, as measured by resolubilisation, was Very dependent on pH and ionic strength, suggesting that electrostatic forces dominate the protein-protein attractive forces in the aggregate. However, a marked temperature dependence indicated that hydrogen bond stabilisation of the aggregate could also be significant. Spectral analysis of the solutions and precipitates suggested that the haem environment in the pressure-denatured state was typical of the ferric pigment of heat-denatured myoglobin. However, the initial colour of suspensions following pressure denaturation changed rapidly on standing and may indicate that the initial product of pressure treatment is a very unstable complex that rapidly converts to the denatured ferric pigment.