i fucking hate this class

biochem is shit

What are the two outcomes for pyruvate generated through glycolysis?

• Fermentation

• Aerobic Respiration

What happens with pyruvate and aerobic respiration?

Pyruvate gets transported into the mitochondria and converted into acetyl CoA for entry into TCA

What is the overall reaction catalyzed by the PDH complex?

Pyruvate + CoA + NAD+ → Acetyl CoA + CO2 + NADH + H+

Is the reaction that the PDH complex catalyzes reversible or irreversible?

irreversible

How is glycolysis linked to the citric acid cycle?

After glycolysis occurs, pyruvate is produced and then enters the mitochondria if O2 is present to be converted into acetyl-CoA to start TCA

What are the three main steps the PDH complex catalyzed reaction can be broken down into?

• Decarboxylation

• Oxidation

• Transfer to CoA

What is the purpose of the PDH complex and where is it located?

• Pyruvate Dehydrogenase Complex

  • Performs the conversion of pyruvate to acetyl-CoA for the TCA

  • PDH is located in the mitochondrial matrix

How does the PDH complex reaction work?

• Transport

  • Pyruvate crosses the mitochondrial membrane using MPC1 and MPC2

• Conversion

  • It undergoes oxidative decarboxylation, loses a carbon and gets attached to CoA to form acetyl-CoA

What are the stoichiometric coenzymes of the PDH complex?

• NAD+ and CoA

  • they act as reactants/substrates and get used up in each reaction must be replenished

What are the catalytic coenzymes of the PDC?

• Tpp, Lipoamide, FAD

  • are not permanently altered during their reactions, can be reset and reused

What is E1 purpose?

• Group: Tpp

  • It catalyzes oxidation decarboxylation of pyruvate

What is E2 purpose?

• Group: Lipoamide

  • Catalyzes the transfer of acetyl group to CoA

What is E3 purpose?

• Group: FAD

  • Catalyzes the regeneration of the oxidized form of the lipoamide

What happens to the reduced lipoamide after the cycle is completed?

• It must be reoxidized

  • E3 helps transfers electrons to FAD, then from FAD to NAD+

  • Weird… electrons in NADH have better transfer potential but instead are transferred through FAD first

How does the lipoamide move between the different active sites in the PDC?

It has flexible linkages to do so, the enzymes are closely arranged to work together efficiently

What happens because the reaction is irreversible?

The acetyl-CoA can only be used for oxidation in TCA or incorporated into fatty acids

High concentrations of what inhibit the complex?

• Acetyl-CoA inhibits → E2

• NADH inhibits → E3

This spares glucose when needs are met

What does phosphorylation of E1 cause?

It inactives the complex

• PDK adds the Pi turning the PDH off

• PDP removes the Pi, turning it back on

What does acetyl CoA inhibit?

E2

What does NADH inhibit?

E3

What activates the PDH kinase?

High levels of:

• NADH to NAD+

• Acetyl CoA to CoA

• ATP to ADP

What inhibits the PDH kinase?

Inhibited by

• ADP

• Pyruvate

What does the PDH kinase do?

It regulates the activity of the PDH by phosphorylating