PFK-1 Activator Identification
Phosphofructokinase-1 (PFK-1) is a key regulatory enzyme controlling a major step in glycolysis. Its activity is modulated by allosteric effectors, including activators and inhibitors.
Role of Fructose 2,6-bisphosphate
Fructose 2,6-bisphosphate is recognized as a highly potent and physiologically significant allosteric activator of PFK-1. It enhances the enzyme's affinity for fructose-6-phosphate and alleviates inhibition by ATP. This molecule plays a central role in coordinating the rates of glycolysis and gluconeogenesis in response to hormonal signals.
Analysis of Other Options
- Fructose 1,6-bisphosphate: This molecule, a product of the PFK-1 reaction, also serves as a feedback activator. However, Fructose 2,6-bisphosphate is generally considered a more powerful and upstream regulator.
- Glucose 6-phosphate: This early glycolytic intermediate typically acts as an inhibitor of PFK-1, not an activator.
- Citrate: Originating from the citric acid cycle, citrate signals sufficient energy reserves and functions as an allosteric inhibitor of PFK-1, thereby suppressing glycolysis.
Based on established biochemical regulation, Fructose 2,6-bisphosphate is the most appropriate answer for a potent allosteric activator of PFK-1 among the options.
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
