ATP Flashcards
What are the endergoni processes in metabolism driven by?
The exergonic reactions of nutrient oxidation with mediation by high-energy intermediates.
What is the structure of ATP?
An adenosine molecule linked by three phosphoryl groups, seperated by phosphoanhydride bonds.
What are the two general reaction pathways of ATP?
ATP + H20 <==> ADP +Pi
ATP + H20 <==> AMP +2 Pi
What is an example of ATP coupling?
Hexokinase G phosphorylation forming G6P.
Why is Hexokinase required for G phosphorylation?
Pi and G interaction is unfavourable so exergonic hydrolysis of ATP provides thermodynamic favourability.
What are the two key features of phosphoryl-transfer reactions?
Kinetic stability to hydrolysis and capacity to transmit large amounts of free energy.
Describe the functional importance of glycolysis in terms of energy?
Phosphoryl-transfer potential of glucose to G6P is -16.7kJ whilst PEP dephos to pyruvate is -61.9kJ.
Phosphoryl Transfer Potential
The standard free energy of hydrolysis.
What does phosphoryl transfer potential measure?
Tendency of phosphorylated compounds to transfer phosphoryl groups to water.
Why does phosphoryl transfer potential fluctuate with pH?
Increased divalent cation concentration of say Mg2+ of which has binding affinity for phosphoate.
What is a high energy bond?
A bond in which hydrolysis can generate 30kJ of energy to drive unfavourable reactions forwards.
Phosphoanhydride bond
A chemical bond formed between two phosphate groups.
What are the three characteristics of phosphoanhydride bonds of its high free energy release?
Its ressonance
Electrostatic repulsions between phosphate groups
Low solvation energy.
What does resonance allow for?
Electronic delocalisation with greater electronic occupation of volume so lower overall molecular energy.
What is increasing resonance proportional to?
More resonance more stability.
