Your data show that kcat increases as hyperbola and 1/kcat decreases as hyperbola when the concentration of modifier increases, namely
This property is shared by five basic modifier mechanisms. Two of them (the left and right choices below) can be identified just by examining the dependence of Km on modifier concentration, [X].
For the subgroup ‘Km increases as hyperbola’ (the choice in the middle) discrimination is made by further examining how kcat/Km varies with [X]. Click the appropriate statement to unravel the mechanism.
Km decreases as hyperbola
The sought mechanism is:
Hyperbolic mixed, predominantly catalytic activation, HMx(Sp<Ca)A
Km increases as hyperbola
Three mechanisms share this property and can be distinguished from the dependencies of kcat/Km on modifier concentration.
Km is independent of modifier concentration
