Nanosecond fluorometric investigation of hydrodynamic properties of adenosine triphosphatase from thermophilic bacterium PS3.
The soluble portion (TF1) of proton-translocating ATPase from thermophilic bacterium PS3 was labeled with a fluorescent dye N-(1-pyrene)maleimide. The decay of fluorescence anisotropy of the adduct showed that TF1 in aqueous solution was characterized by a volume of equivalent sphere of 1,120 nm3. This value is 2.4 times the volume calculated from the molecular weight and partial specific volume, indicating a non-spherical shape and/or extensive hydration. A prolate ellipsoid with an axial ratio of 2 to 3 is suggested as a first approximation of the shape of hydrated TF1. The presence or absence of ATP, ADP, or Mg2+ did not alter the volume of the equivalent sphere appreciably; the probable conformational change of TF1 induced by these ligands does not lead to a gross alteration of its hydrodynamic properties.
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D001419:Bacteria / Q000378:metabolism; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D005454:Fluorescence Polarization / Q000379:methods; D008970:Molecular Weight; D014867:Water
D014867:Water; D000251:Adenosine Triphosphatases