Metabolite Hydrolysis Energy Analysis
The question requires identifying a group of metabolites where every compound's bond hydrolysis has a standard free energy change (${\Delta}G'^{\circ}$) of -7.0 kcal/mole or less. This value represents a "high-energy" bond that can readily release energy for biological processes.
Standard Free Energy of Hydrolysis Data
The approximate standard free energy of hydrolysis (${\Delta}G'^{\circ}$) values (in kcal/mole under standard biochemical conditions) for relevant metabolites are listed below:
| Metabolite | Hydrolysis Reaction | ${\Delta}G'^{\circ}$ (kcal/mole) |
|---|---|---|
| ATP | ATP + H2O → ADP + Pi | ~ -7.3 |
| ADP | ADP + H2O → AMP + Pi | ~ -7.3 |
| Glucose 1-phosphate | Glucose 1-P + H2O → Glucose + Pi | ~ -5.0 |
| Fructose 1,6-bisphosphate | Fructose 1,6-bis-P + H2O → Fructose-6-P + Pi | ~ -3.4 |
| Creatine phosphate | Creatine-P + H2O → Creatine + Pi | ~ -10.3 |
| Acetyl phosphate | Acetyl-P + H2O → Acetate + Pi | ~ -11.1 |
| Succinyl CoA | Succinyl CoA + H2O → Succinate + CoA | ~ -7.6 |
| Glycerol 3-phosphate | Glycerol 3-P + H2O → Glycerol + Pi | ~ -2.2 |
| Acetyl CoA | Acetyl CoA + H2O → Acetate + CoA | ~ -7.5 |
| 1,3-Bisphosphoglycerate | 1,3-BPG + H2O → 3-PG + Pi | ~ -11.4 |
| Glucose 6-phosphate | Glucose 6-P + H2O → Glucose + Pi | ~ -3.3 |
| Phosphoenolpyruvate (PEP) | PEP + H2O → Pyruvate + Pi | ~ -14.8 |
Evaluating Metabolite Groups for High-Energy Bonds
We examine each option to see if all listed metabolites meet the ${\Delta}G'^{\circ} \leq$ -7.0 kcal/mole condition.
Option 1 Assessment
- Glucose 1-phosphate: ~ -5.0 kcal/mole (Does not meet criterion)
- ATP: ~ -7.3 kcal/mole (Meets criterion)
- Fructose 1,6-bisphosphate: ~ -3.4 kcal/mole (Does not meet criterion)
This group is invalid as two compounds do not have high-energy phosphate bonds.
Option 2 Assessment
- Creatine phosphate: ~ -10.3 kcal/mole (Meets criterion)
- Acetyl phosphate: ~ -11.1 kcal/mole (Meets criterion)
- Succinyl CoA: ~ -7.6 kcal/mole (Meets criterion)
All compounds in this group satisfy the condition of having ${\Delta}G'^{\circ} \leq$ -7.0 kcal/mole.
Option 3 Assessment
- Glycerol 3-phosphate: ~ -2.2 kcal/mole (Does not meet criterion)
- Acetyl CoA: ~ -7.5 kcal/mole (Meets criterion)
- 1,3-Bisphosphoglycerate: ~ -11.4 kcal/mole (Meets criterion)
This group is invalid because Glycerol 3-phosphate's hydrolysis energy is too low.
Option 4 Assessment
- Glucose 6-phosphate: ~ -3.3 kcal/mole (Does not meet criterion)
- Phosphoenolpyruvate (PEP): ~ -14.8 kcal/mole (Meets criterion)
- ADP: ~ -7.3 kcal/mole (Meets criterion)
This group is invalid as Glucose 6-phosphate does not meet the criterion.
Final Determination
Based on the analysis of standard free energy of hydrolysis values, Option 2 is the only group where all listed metabolites contain at least one bond with ${\Delta}G'^{\circ} \leq$ -7.0 kcal/mole.
Important Questions from Bioenergetics ATP Hydrolysis
- Assuming that there are $5 \times 10^{13}$ cells in the human body, and that ATP is turning over at a rate of $10^9$ ATP molecules per minute in each cell, then the human body is utilizing ________ watts (rounded off to two decimal places).
[Assume that hydrolysis of ATP yields 12 kcal per mole. 1 watt = 1 joule/sec, 1 calorie = 4.18 joules, Avogadro's number = $6.023 \times 10^{23}$] - Glucose and hexanoic acid, each having six carbon atoms can undergo complete biological oxidation. In terms of net ATP generation, which of the following statements is CORRECT?
- Which one of the following statements is NOT correct?
- Which of the following is TRUE about Kreb's cycle?
- The movement of protons through the $F_0F_1$-ATPase during mitochondrial respiration is required for ________
