Equilibrium Constant Calculation for Phosphoglucose Isomerase
The reaction involves the interconversion of glucose 6-phosphate (G6P) to fructose 6-phosphate (F6P) catalyzed by phosphoglucose isomerase.
Reaction: Glucose 6-phosphate $\rightleftharpoons$ Fructose 6-phosphate
Determining Equilibrium Concentrations
We are given that 55% of the initial glucose 6-phosphate is converted to fructose 6-phosphate at equilibrium. This means 45% of the glucose 6-phosphate remains.
- Percentage conversion = 55%
- Percentage remaining = 100% - 55% = 45%
Let the initial concentration of glucose 6-phosphate be $[G6P]_0$. The equilibrium concentrations are:
- $[G6P]_{eq} = 0.45 \times [G6P]_0$
- $[F6P]_{eq} = 0.55 \times [G6P]_0$
Calculating Equilibrium Constant ($K_{eq}$)
The equilibrium constant ($K_{eq}$) is defined as the ratio of the product concentrations to the reactant concentrations at equilibrium.
Formula: $K_{eq} = \frac{[\text{Fructose 6-phosphate}]_{eq}}{[\text{Glucose 6-phosphate}]_{eq}}$
Substituting the equilibrium concentrations:
$K_{eq} = \frac{0.55 \times [G6P]_0}{0.45 \times [G6P]_0}$
The initial concentration term $[G6P]_0$ cancels out:
$K_{eq} = \frac{0.55}{0.45}$
$K_{eq} = \frac{55}{45} = \frac{11}{9}$
Calculating the value:
$K_{eq} \approx 1.222$
This value lies between 1.2 and 1.24, confirming the provided range.
Important Questions from Metabolism Glycolysis Nucleotide
- The oxidative phase of the hexose monophosphate pathway generates ________ moles of NADPH per mole of glucose 6-phosphate (answer in integer).
- Which one of the following enzymes is NOT inhibited by glucose-6-phosphate?
- Assume that in the oxidative branch of the pentose phosphate pathway, each glucose-6-phosphate molecule generates the following products: 2 molecules of NADPH, 1 molecule of $\text{CO}_2$ and 1 molecule of ribulose-5-phosphate.
If 30 molecules of glucose-6-phosphate enter this pathway, and you randomly draw one molecule from the products of the pathway, the probability that this molecule is NADPH is __________ (round off to one decimal place). - Match the hormones in Group I with their metabolic precursor in Group II
Group I Group II P. 17-$\beta$ estradiol 1. Arachidonic acid Q. Thromboxane A2 2. Tyrosine R. Epinephrine 3. $\beta$-carotene S. Retinoic acid 4. Cholesterol Which of the following statements are TRUE for respiration?
P. The conversion of one molecule of pyruvate to three molecules of $CO_2$ generates four molecules of NADH
Q. Fructose 6-phospate is the principal substrate for glycolysis
R. The oxidation of glucose 6-phosphate to 6-phosphogluconate is the first step in the oxidative pentose phosphate pathway
S. The mitochondrial 'alternative oxidase' provides an alternative pathway for transfer of electrons from ubiquinone to oxygen utilizing proton pumping complex of the respiratory chain
