Premium
Phenylalanine Ammonia Lyase Catalyzed Synthesis of Amino Acids by an MIO‐Cofactor Independent Pathway
Author(s) -
Lovelock Sarah L.,
Lloyd Richard C.,
Turner Nicholas J.
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201311061
Subject(s) - deamination , phenylalanine , chemistry , amino acid , decarboxylation , cofactor , oxidative deamination , stereochemistry , ammonia , enantioselective synthesis , enzyme , phenylalanine ammonia lyase , transamination , biochemistry , active site , biosynthesis , aspartic acid , catalysis
Abstract Phenylalanine ammonia lyases (PALs) belong to a family of 4‐methylideneimidazole‐5‐one (MIO) cofactor dependent enzymes which are responsible for the conversion of L ‐phenylalanine into trans ‐cinnamic acid in eukaryotic and prokaryotic organisms. Under conditions of high ammonia concentration, this deamination reaction is reversible and hence there is considerable interest in the development of PALs as biocatalysts for the enantioselective synthesis of non‐natural amino acids. Herein the discovery of a previously unobserved competing MIO‐independent reaction pathway, which proceeds in a non‐stereoselective manner and results in the generation of both L ‐ and D ‐phenylalanine derivatives, is described. The mechanism of the MIO‐independent pathway is explored through isotopic‐labeling studies and mutagenesis of key active‐site residues. The results obtained are consistent with amino acid deamination occurring by a stepwise E 1 cB elimination mechanism.