Question

The enzyme glucose 6-phosphate dehydrogenase catalyzes the first step of the Pentose Phosphate Pathway (we will study this pathway after the exam). Based strictly on the KM values of the three potential substrates listed below, which of them would best interact with this enzyme and be converted to product?

Compound KM
fructose 6-phosphate 1.5 mM
glucose 6-phosphate 0.05 mM
galactose 6-phosphate 0.02 mM

Answer 1

Answer and Explanation:

By michaelis mentos equation

Rate of reaction, $V_0 = \frac{V_{max}[S]}{K_m + [S]}$

where $K_m$ is michaelis mentos constant

For same value of Vmax and [S] the rate of reaction will be higher for that as lowest(minimum) value of Km

Here for galactose-6-phosphate the Km value is minimum (Km = 0.02 mm)

So "Galactose-6-phosphate" will best interact with this enzyme and be converted to product