L-serine ammonia-lyase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: L-serine = pyruvate + NH3. [EC:4.3.1.17]

L-serine ammonia-lyase activity, also known as serine dehydratase, is a crucial enzyme involved in the catabolism of L-serine. It catalyzes the irreversible conversion of L-serine into pyruvate and ammonia, a key step in the biosynthesis of several amino acids, including cysteine and glycine. The reaction proceeds through a series of steps, starting with the abstraction of a proton from the α-carbon of L-serine by a base, typically a lysine residue in the active site of the enzyme. This results in the formation of a carbanion intermediate. Subsequently, the carbanion undergoes elimination of ammonia, generating an α,β-unsaturated intermediate. Finally, the unsaturated intermediate undergoes a protonation reaction, yielding pyruvate. The enzyme's active site typically contains a pyridoxal-5'-phosphate (PLP) cofactor, which plays a critical role in the catalytic mechanism. PLP acts as an electron sink, facilitating the formation and stabilization of the carbanion intermediate. Moreover, the PLP cofactor is involved in the elimination of ammonia, forming an external aldimine intermediate. This intermediate then undergoes a tautomerization reaction, resulting in the formation of an internal aldimine, which eventually yields pyruvate and ammonia. This intricate mechanism highlights the enzyme's essential role in cellular metabolism, contributing to the synthesis of essential amino acids and the regulation of metabolic pathways.'
"

Proteins (1)

Compounds (9)