title: Enzymatic synthesis of enantiopure alpha- and beta-amino acids by phenylalanine aminomutase-catalysed amination of cinnamic acid derivatives.
abstract: The phenylalanine aminomutase (PAM) from Taxus chinensis catalyses the conversion of alpha-phenylalanine to beta-phenylalanine, an important step in the biosynthesis of the N-benzoyl phenylisoserinoyl side-chain of the anticancer drug taxol. Mechanistic studies on PAM have suggested that (E)-cinnamic acid is an intermediate in the mutase reaction and that it can be released from the enzyme's active site. Here we describe a novel synthetic strategy that is based on the finding that ring-substituted (E)-cinnamic acids can serve as a substrate in PAM-catalysed ammonia addition reactions for the biocatalytic production of several important beta-amino acids. The enzyme has a broad substrate range and a high enantioselectivity with cinnamic acid derivatives; this allows the synthesis of several non-natural aromatic alpha- and beta-amino acids in excellent enantiomeric excess (ee >99 %). The internal 5-methylene-3,5-dihydroimidazol-4-one (MIO) cofactor is essential for the PAM-catalysed amination reactions. The regioselectivity of amination reactions was influenced by the nature of the ring substituent.
authors.affiliation: Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
authors.forename: Bian
authors.initials: B
authors.lastname: Wu
authors.forename: Wiktor
authors.initials: W
authors.lastname: Szymanski
authors.forename: Piet
authors.initials: P
authors.lastname: Wietzes
authors.forename: Stefaan
authors.initials: S
authors.lastname: de Wildeman
authors.forename: Gerrit J
authors.initials: GJ
authors.lastname: Poelarends
authors.forename: Ben L
authors.initials: BL
authors.lastname: Feringa
authors.forename: Dick B
authors.initials: DB
authors.lastname: Janssen
mesh_terms: D000586:Amination; D000641:Ammonia / Q000378:metabolism; D055162:Biocatalysis; D002934:Cinnamates / Q000737:chemistry* / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D007093:Imidazoles / Q000737:chemistry / Q000378:metabolism; D019751:Intramolecular Transferases / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D010649:Phenylalanine / Q000737:chemistry* / Q000378:metabolism*; D013237:Stereoisomerism; D013379:Substrate Specificity; D020946:Taxus / Q000201:enzymology*
chemical_list: D002934:Cinnamates; D007093:Imidazoles; C029010:cinnamic acid; D010649:Phenylalanine; D000641:Ammonia; C029899:imidazole; D019751:Intramolecular Transferases