Amino acid catabolism is the process our bodies use to break down amino acids. This is important for balancing nitrogen and producing energy. Here’s a simple breakdown of the key steps involved:

1. Transamination:
   In this first step, an amino group (which is made up of nitrogen and hydrogen) is passed from one amino acid to another compound called alpha-keto acid. The most common alpha-keto acid is alpha-ketoglutarate, which changes into glutamate. About 90% of amino acids go through this transamination step.

2. Deamination:
   Next, the amino group from glutamate is removed in a process called deamination. This mainly takes place in the liver. Special proteins, known as enzymes (like glutamate dehydrogenase), help with this process. Removing the amino group creates ammonia, which is not safe for our bodies, and also produces alpha-ketoglutarate again.

3. Urea Cycle:
   Since ammonia can be harmful, it is transformed into urea through a series of five reactions known as the urea cycle:

   • First, ammonia and a compound called bicarbonate combine to make carbamoyl phosphate.
   • Then, this compound is turned into citrulline.
   • After that, citrulline combines with another molecule to create argininosuccinate.
   • This molecule is then split into arginine and fumarate.
   • Finally, arginine is broken down to form urea and a compound called ornithine, which can be reused. About half of the ammonia created in our bodies is turned into urea, and our kidneys help get rid of it.

4. Energy Production:
   When amino acids lose their amino group, their remaining parts (carbon skeletons) can be used for energy. They can be turned into glucose, which is a type of sugar, through a process called gluconeogenesis. They can also enter the citric acid cycle, which helps produce a special energy molecule called ATP. It’s thought that amino acids provide around 10% of our daily energy needs when we are healthy.

5. Connection to Other Body Functions:
   Amino acids are also building blocks for many important substances in our bodies. They help create neurotransmitters (which send messages in our brains), hormones (which regulate various functions), and nucleotides (which make up our DNA). This shows how essential amino acids are for overall health and metabolism.

By understanding these steps, we can learn how our bodies process proteins and use them in many important ways.