Low temperature solution behaviour of Methylophilus methylotrophus electron transferring flavoprotein: a study by analytical ultracentrifugation

摘要: The solution behaviour of electron transferring flavoprotein (ETF) from Methylophilus methylotrophus was investigated at low temperature (4 °C) by analytical ultracentrifugation. concentration dependence the apparent weight average molecular weight, Mw,app, established existence protein in heterodimeric state (M = 63,700 Da), but also signified possible dissociation heterodimer lower concentrations into its constituent subunits 28,900 Da and 33,700 Da, together with FAD AMP cofactors collective M 1120 Da). This similarity subunit size allows approximate quantification terms expressions for a monomer-dimer equilibrium. dissociative confirmed determination point Mw,app(r), as function ETF concentration, c(r), throughout sedimentation equilibrium distributions obtained loading 0.4 0.7 mg/ml. By means recently formulated ``psi'' procedure direct analysis solute self-association value (1.5 ± 0.1) µM has been constant Kd. Sedimentation velocity experiments yielded an estimate coefficient, s020,w, (4.5 0.2) S which suggests globular structure.