Lysine decarboxylase

Lysine Decarboxylase

Lysine decarboxylase is an enzyme that plays a crucial role in the metabolism of lysine, an essential amino acid. This enzyme is responsible for catalyzing the decarboxylation of lysine, converting it into cadaverine, a polyamine compound. Lysine decarboxylase is found in various organisms, including bacteria, plants, and animals.

Function

The primary function of lysine decarboxylase is to remove the carboxyl group from lysine, resulting in the formation of cadaverine. This reaction is an important step in the biosynthesis of polyamines, which are involved in various cellular processes, including cell growth, differentiation, and stress response.

Mechanism

Lysine decarboxylase follows a pyridoxal phosphate (PLP)-dependent mechanism. PLP is a cofactor that is essential for the enzyme's activity. It acts as a coenzyme, facilitating the decarboxylation reaction by forming a Schiff base with the lysine substrate. This intermediate undergoes a series of rearrangements, leading to the release of carbon dioxide and the formation of cadaverine.

Role in Bacteria

In bacteria, lysine decarboxylase is often associated with the production of polyamines, which are important for bacterial growth and survival. The conversion of lysine to cadaverine by this enzyme helps maintain the intracellular pH and provides protection against acidic environments. Additionally, cadaverine can act as a precursor for the synthesis of other polyamines, such as putrescine and spermidine.

Role in Plants

Lysine decarboxylase is also present in plants, where it participates in various physiological processes. In plants, polyamines are involved in regulating cell division, embryogenesis, and stress responses. Lysine decarboxylase activity is often upregulated under stress conditions, such as drought, salinity, and pathogen attack, suggesting its role in plant defense mechanisms.

Role in Animals

In animals, lysine decarboxylase is involved in the metabolism of lysine and the synthesis of polyamines. Polyamines are essential for cell proliferation, tissue repair, and immune responses. Dysregulation of lysine decarboxylase activity has been associated with various diseases, including cancer, neurodegenerative disorders, and cardiovascular diseases.

References

1. Smith, T. A., & Smith, R. L. (2019). Lysine decarboxylase: a multifaceted enzyme involved in polyamine biosynthesis. Frontiers in Plant Science, 10, 146.

2. Michael, A. J. (2016). Biosynthesis of polyamines and polyamine-containing molecules. In Polyamines (pp. 1-26). Springer, Cham.

3. Tabor, C. W., & Tabor, H. (1984). Polyamines. Annual Review of Biochemistry, 53(1), 749-790.

See Also

• Polyamines
• Amino Acid Metabolism
• Enzyme Catalysis