Alanine racemase
Alanine racemase is an enzyme that catalyzes the chemical reaction involving the amino acid alanine. This enzyme is found in many bacteria, fungi, and archaea, and plays a crucial role in the synthesis of D-alanine, an essential component of the peptidoglycan layer in bacterial cell walls.
Function[edit | edit source]
Alanine racemase catalyzes the conversion of L-alanine to D-alanine, and vice versa. This reaction is a key step in the biosynthesis of D-alanine, which is a critical component of the peptidoglycan layer in bacterial cell walls. The peptidoglycan layer provides structural integrity to the bacterial cell and protects it from osmotic lysis.
Structure[edit | edit source]
Alanine racemase is a dimeric enzyme, with each monomer composed of two domains. The larger domain, known as the PLP-binding domain, binds the pyridoxal phosphate (PLP) cofactor. The smaller domain, known as the control domain, regulates the activity of the enzyme.
Mechanism[edit | edit source]
The reaction catalyzed by alanine racemase involves the abstraction of a proton from the alpha carbon of L-alanine by a lysine residue in the active site of the enzyme. This results in the formation of a quinonoid intermediate, which is then reprotonated on the opposite face by a tyrosine residue to yield D-alanine.
Clinical significance[edit | edit source]
Because D-alanine is essential for bacterial cell wall synthesis and is not used by humans, alanine racemase is a target for antibacterial drug development. Inhibitors of this enzyme could potentially be used to treat bacterial infections.
See also[edit | edit source]
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