1984 年 7 巻 2 号 p. 100-107
Inhibitory action of copper ion (Cu2+) on β-galactosidase (β-Gase) and dehydrogenases (DHases) of activated sludge is studied.
Cu2+ shows powerful inhibition for the activities of β-Gase and DHases. The concentration of Cu2+ which reduces 50% of the activities of β-Gase and DHases are about 0.08μmole/mg activated sludge and 0.01μmole/mg activated sludge, respectively.
The inhibition by Cu2+ of the activities of β-Gase and DHases are reversible since the activities inhibited are easily recovered with addition of excess thiols. Reactivation by thiols suggests that Cu2+ forms reversible mercaptides with SH groups of β-Gase and DHases.
The Kinetic studies indicate that the inhibition by Cu2+ of the activities of β-Gase and DHases gives reversible non-competitive type of kinetics. Ki values of β-Gase and DHases against Cu2+ are calculated to be 0.1mM (MLSS 1050mg/1 : 0.095μmole Cu2+/mg activated sludge) and 0.02mM (MLSS 2110mg/1 : 0.01μmole Cu2+/mg activated sludge), respectively.