Question

Both amino acid decarboxylase and tryptophan synthase are enzymes involving pyridoxal phosphate (PLP) in their mechanisms. There are both similarities and differences between the two mechanisms. For each of the statements describing a mechanism feature, indicate whether it is a feature of the decarboxylase, the synthase, or both.

Amino acid decarboxylase Tryptophan synthase Both Answer Bank PLP forms a quinonoid structure when electrons are delocalized from the amino acid. Active sites on two different subunits are involved in the reaction. Both the substrate and product are amino acids. The amino acid displaces an enzyme lysine residue in forming a PLP aldimine derivative. PLP facilitates sigma bond breakage at the B-carbon of the amino acid. PLP facilitates sigma bond breakage only at the a-carbon of the amino acid.

Answer 1

Aminoacid decarboxylase Tryptophan eystrase PLP, torms a quinonoid structure when are delocalixed from the amino acid. Active sites on two different subunite are involved in the reaction. Both the substrate and ! PLP facilitates sigma bond breakage at the Bearbon of the aminoacid product are aminoacids PLP Facilitatea sigma bond breakage only at the x- carbons of the amino acid lysine Both The aminoacid displaces an residue in forming a PLP derivative enzyme aldimine