TEMPERATURE-DEPENDENCE OF SPECTROSCOPIC AND CATALYTIC PROPERTIES OF THE EEL (ANGUILLA-ANGUILLA) LIVER MITOCHONDRIAL F1-ATPASE

1. F1-ATPase from eel liver mitochondria at low concentrations preserves unaltered the enzymatic activity for more than 20 min over a temperature range of 6-36-degrees-C. 2. The Arrhenius plot of ATP hydrolysis at saturating substrate concentration appears biphasic with a break-point at 16-degrees-C and activation energies of 14.4 and 56.1 kJ/mol. 3. The ultraviolet, fluorescence and circular dichroism spectra of the enzyme, below and above 16-degrees-C, have been recorded; the fluorescence emission spectra of F1-ATPase excited at 275 nm, and the circular dichroism spectra, are different at the two temperatures examined. 4. It is concluded that temperature induces two different conformational states of F1-ATPase with different catalytic properties. 5. Ultraviolet spectroscopic features and temperature-dependence of eel liver mitochondrial F1-ATPase are discussed in relation to mammalian F1-ATPases.