Effect of High Pressure, Detergents and Phaospholipase on the Break in the Arrhenius Plot of Azotobacter Nitrogenase

Abstract

Lipids are responsible for the breaks in the Arrhenius plots of Azotobacter [vinelandii] nitrogenase. The physical evidence is that temperature at which the break occurs increases with increasing pressure by 20.degree. K/1000 atm. This is in agreement with the pressure dependence of the transition temperature of several synthetic phospholipids. The same pressure dependence was also found for the broad transitions observed in Escherichia coli phosphatidylethanolamine and in the membrane lipids from Azotobacter itself. Detergents and phospholipase remove the break. Reconstruction can be performed only with specific phospholipids.