Biosynthesis of proteins from amino acids is an energy driven condensation process (ÄH = + 10
kJ/mol) requiring energy input in the form of ATP. In an experiment, 0.4 mol of amino acids
reacted to give a polypeptide and some ATP was consumed.
a) explain how biosynthesis of proteins is energy-coupled to the hydrolysis of ATP.
b) calculate the amount of ATP (in moles) used in the experiment if the amount of dissipated heat of 14.3 kj
a) Biosynthesis of proteins is energy-coupled to the hydrolysis of ATP through a process called phosphorylation. In this process, ATP molecules are hydrolyzed, releasing energy, and one of the phosphate groups is transferred to an amino acid molecule, forming a high-energy phosphorylated amino acid. This phosphorylation reaction requires ATP as an energy source.
The phosphorylated amino acid molecule then undergoes a condensation reaction with another amino acid molecule. During this condensation reaction, a peptide bond is formed between the two amino acids, releasing water as a byproduct. This condensation process is energetically favorable (ΔH = -10 kJ/mol) and is coupled to the energy released from ATP hydrolysis.
Overall, the biosynthesis of proteins from amino acids requires the energy input from ATP hydrolysis to drive the condensation reactions and overcome the thermodynamic barrier.
b) To calculate the amount of ATP used in the experiment, we need to use the given information about the dissipated heat.
Given:
Amount of dissipated heat (ΔH) = 14.3 kJ
ΔH for biosynthesis of proteins (ΔH_reaction) = +10 kJ/mol
We can use the equation:
ΔH_reaction = -nΔH_ATP
Where:
n is the number of moles of ATP used.
Rearranging the equation, we have:
n = -ΔH_reaction / ΔH_ATP
Substituting the given values:
n = -10 kJ/mol / -14.3 kJ
Simplifying, we get:
n = 0.7 mol
Therefore, the amount of ATP used in the experiment is approximately 0.7 moles.