Transaminases

Definition

Transaminases, also known as aminotransferases, are enzymes that catalyze the transfer of an amino group from one molecule to another. They play a crucial role in the catabolism of proteins by facilitating the deamination process, which is the removal of the amino group from amino acids.

5 Must Know Facts For Your Next Test

1. Transaminases catalyze the transfer of the amino group from an amino acid to an alpha-keto acid, forming a new amino acid and a different alpha-keto acid.
2. The two most common transaminases are alanine transaminase (ALT) and aspartate transaminase (AST), which are often used as biomarkers for liver damage or disease.
3. Transaminases play a key role in gluconeogenesis, the process of synthesizing glucose from non-carbohydrate precursors, such as amino acids.
4. The activity of transaminases can be influenced by various factors, including diet, exercise, and certain medical conditions, making them important clinical indicators.
5. Inhibition or dysfunction of transaminases can lead to the accumulation of amino acids and the disruption of normal metabolic pathways, potentially contributing to various disease states.

Review Questions

• Explain the role of transaminases in the catabolism of proteins and the deamination process.
  • Transaminases are essential enzymes in the catabolism of proteins, as they facilitate the deamination process. Deamination is the removal of the amino group (NH2) from an amino acid, resulting in the formation of an alpha-keto acid and the release of ammonia. Transaminases catalyze this reaction by transferring the amino group from the amino acid to an alpha-keto acid, creating a new amino acid and a different alpha-keto acid. This process allows the body to break down and utilize amino acids as a source of energy or for other metabolic processes, while also generating ammonia, which must be converted to urea for excretion.
• Describe the clinical significance of measuring transaminase levels, particularly alanine transaminase (ALT) and aspartate transaminase (AST).
  • Alanine transaminase (ALT) and aspartate transaminase (AST) are the two most commonly measured transaminases in clinical settings. These enzymes are often used as biomarkers for liver damage or disease, as they are released into the bloodstream when liver cells are injured or destroyed. Elevated levels of ALT and AST can indicate conditions such as hepatitis, cirrhosis, fatty liver disease, and even certain types of cancer. Monitoring transaminase levels can help healthcare providers diagnose and monitor the progression of liver-related disorders, as well as evaluate the effectiveness of treatment interventions. The relative levels of ALT and AST can also provide insights into the specific type of liver injury or disease present.
• Analyze the potential consequences of inhibition or dysfunction of transaminases, and how this can impact overall metabolic pathways and health.
  • Inhibition or dysfunction of transaminases can have significant consequences for an individual's health and overall metabolic processes. If transaminases are unable to efficiently catalyze the transfer of amino groups, it can lead to the accumulation of amino acids and disrupt normal metabolic pathways. This can contribute to the development of various disease states, such as hyperammonemia (excessive ammonia in the blood), which can cause neurological symptoms and organ damage if left untreated. Additionally, the disruption of transaminase activity can impair gluconeogenesis, the process of synthesizing glucose from non-carbohydrate precursors like amino acids. This can have implications for energy metabolism and glucose homeostasis, potentially leading to conditions like hypoglycemia or metabolic disorders. Understanding the critical role of transaminases in maintaining healthy protein catabolism and broader metabolic functions is essential for identifying and managing any issues related to their inhibition or dysfunction.

Related terms

Deamination: The process of removing the amino group (NH2) from an amino acid, resulting in the formation of an alpha-keto acid and the release of ammonia.

Alpha-keto Acid: The product of deamination, where the amino group is removed from an amino acid, leaving behind a carboxylic acid with a keto group at the alpha carbon.

Ammonia: The byproduct of deamination, which is a toxic compound that must be converted to urea for excretion.