The effect of high hydrostatic pressure on stability of pyruvate oxidase from aeroccocus species
Wallace, Luke Smith
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Pyruvate oxidase (POX) catalyzes the oxidative decarboxylation of pyruvate to acetylphosphate in the presence of oxygen, a divalent cation, and its cofactors thiamine pyrophosphate and flavin adenine dinucleotide. High hydrostatic pressure (HHP) was applied at selected temperatures to elucidate its effect on the thermostability of POX. High pressure generally destabilizes POX. Rate of inactivation was slowed slightly between atmospheric pressure and 50 MPa at 35 °C, where kinact decreased from 0.004 ± 0.003 min-1 to 0.001 ± 0.001 min-1. Activation volume halved to 29 ± 13 cm3/mol at 45 °C from 68 ± 43 cm/mol at 35 °C and 71 ± 12 cm/mol at 25 °C. Data from non-denaturing gel electrophoresis and ultraviolet spectroscopy suggest that POX remains in a native conformation before dissociating and precipitating with the application of HHP. Low density polyethylene reduced POX activity, though the specific reason for this affect is unclear.