Lecture 3: Amino Acids

Question 1

How do amino acids contribute to oxidative metabolism?

Answer 1

• Amino acids cannot simply be shared.
• They can be converted to glucose during starvation.
• Very few amino acids are lost and most are ultimately oxidised.
• Metabolism mainly occurs in the muscle (due to bulk) and liver (as it is the first organ to get amino acids).

Question 2

How are branched chain amino acids used?

Answer 2

The branched chain amino acids are leucine, isoleucine and valine.
• The use of branched chain amino acid depends on concentration, not insulin.
• Some the BCAAs are used for protein while some are used to make TCA interediates.

Question 3

How do alanine and glutamine synthesis work?

Answer 3

Ala and Glu synthesis provides a link between glucose and amino acid metabolism.
• Ala and Glu comprise most of the most amino acids leaving the muscle, adipose and brain.
• Glucose undergoes glycolysis, producing pyruvate. Pyruvate is then converted to alanine. Alanine can be used in the liver, especially during gluconeogenesis.
• Glutamine is synthesised from α-KG but not directly from the TCA cycle. It is likely from the anaplerotic reactions of leucine, valine and isoleucine.