Studies on an ATPase of thermophilic bacteria

摘要: Abstract ATPase (EC 3.6.1.3) from Bacillus stearothermophilus is purified to a state in which it homogeneous, both ultracentrifugally and electrophoretically. The sedimentation constant molecular weight are 11.9 S 280 000, respectively, the optimum pH 8.0 or 8.5, Tris-acetate Tris-maleate buffer. Divalent cations such as Mg2+, Mn2+ Cd2+ activate enzyme but activity strongly inhibited by I2, N3− CN−. Sulfhydryl reagents uncouplers have no effect on activity. ADP inhibits mode of inhibition appears be different that mesophiles. proline content low (4.3 g/100 g protein) average amount contained protein thermophilic bacteria also similar mesophilic bacteria. contains about 20% α-helical conformation. increases gradually with increasing temperature, above 50° abruptly. has an temperature 65° exhibits remarkable resistance thermal inactivation; these results may indicate not only thermostable thermophilic. Thermodynamic quantities for enzyme, calculated range 30–65°, suggest conformational change occurs at transition 55°.