Question

g In the absence of allosteric effectors, the enzyme phosphofructokinase displays Michaelis–Menten kinetics (see Fig. 7.15). The v0/Vmax ratio is 0.90 when the concentration of the substrate, fructose-6-phosphate, is 0.10 mM. Calculate the KM for phosphofructokinase under these conditions (in units of mM).

Answer 1

Answer:

The value of the Michaelis–Menten constant is 0.0111 mM.

Explanation:

Michaelis–Menten 's equation:

$v_o=V_{max}\times \frac{[S]}{(K_m+[S])}=k_{cat}[E_o]\times \frac{[S]}{(K_m+[S])}$

$V_{max}=k_{cat}[E_o]$

Where:

$v_o$ = rate of formation of products

[S] = Concatenation of substrate

$[K_m]$ =  Michaelis constant

$V_{max}$  = Maximum rate achieved

$k_{cat}$ = Catalytic rate of the system

$[E_o]$ = Initial concentration of enzyme

On substituting all the given values

We have :

$\frac{v_o}{V_{max}}=0.90$

[S] = 0.10 mM

$\frac{v_o}{V_{max}}=\frac{[S]}{(K_m+[S])}$

$0.90=\frac{0.10 mM}{K_m+0.10 M}$

$K_m=0.0111 mM$

The value of the Michaelis–Menten constant is 0.0111 mM.