A study of kinetic properties of mitochondrial
ATPase in
Morris hepatoma 3924A is reported. The results show that submitochondrial particles isolated from the
tumor tissue exhibited a three-fold increase in both the Km for
ATP hydrolysis and Ki for the competitive inhibitor [
beta, gamma-imido]ATP with regard to normal rat liver. Eadie-Hofstee analysis of the kinetics of
ATP hydrolysis show that both the high and the low affinity constants for
ATP were enhanced in the
hepatoma with respect to the rat liver
enzyme. Kinetic analysis of passive
proton conduction through the F0 sector of
ATPase does not reveal any difference between
Morris hepatoma and rat liver. In
Morris hepatoma particles, 50% inhibition of the
hydrolase activity required 10 times more
oligomycin than in control particles. On the contrary, 50% inhibition of
proton conduction occurred in both
hepatoma and rat liver particles at the same concentration of
oligomycin. It is concluded that in
Morris hepatoma the catalytic process in F1 and the functional connection between F1 and F0 of the
ATP synthase are altered with regard to control rat liver.