Protein is a polypeptide chain of amino acids joined together by a peptide linkage.
These individual amino acids make the fundamental building blocks of all life.
It is involved in almost all biological functions in a living system including growth, metabolism, cell signalling, immunity, and many more.
Some amino acids called non-essential amino acids such as glutamine, glycine, proline, serine, etc can be synthesized in our body, while other essential amino acids like isoleucine, leucine, lysine, methionine, etc have to be consumed only through diet.
These amino acids that are formed as a by-product of metabolic reactions are broken down, degraded, or maybe recycled.
Acetyl CoA
Acetyl CoA is a biological molecule utilized in many biological chemical cycles and metabolic pathways.
It is a molecule composed of an acyl group carrier, acetic acid, a thiol and coenzyme A linked by a thioester bond.
The main role is to provide an acetyl group to the oxidation reactions performed in the Krebs cycle in order to generate energy.
Protein recycling process
During protein breakdown, the individual amino acids can be recycled and reused as a substrate for other biochemical reactions.
The polypeptide chains are broken down into their constituent amino acids through protease.
Amino acids having a keto group like leucine, lysine, etc are called ketogenic amino acids and are broken down through catabolic reactions into acetyl CoA.
This acetyl CoA is then used as a substrate for Krebs's cycle.
The carbon skeleton of these amino acids is used for the Citric acid cycle.
Kreb's cycle or Citric acid cycle is a part of glucose metabolism and the carbon skeleton of these amino acids is reused in this process.
This establishes a direct connection between protein and glucose metabolism.
