title: Enzymatic production of L-tryptophan from DL-serine and indole by a coupled reaction of tryptophan synthase and amino acid racemase.
abstract: Enzymatic production of L-tryptophan from DL-serine and indole by a coupled reaction of tryptophan synthase and amino acid racemase was studied. The tryptophan synthase (EC 4.2.1.20) of Escherichia coli catalyzed beta-substitution reaction of L-serine into L-tryptophan and the amino acid racemase (EC 5.1.1.10) of Pseudomonas putida catalyzed the racemization of D-serine simultaneously in one reactor. Under optimal conditions established for L-tryptophan production, a large-scale production of L-tryptophan was carried out in a 200-liter reactor using intact cells of E. coli and P. putida. After 24 h of incubation with intermittent indole feeding, 110 g liter-1 of L-tryptophan was formed in molar yields of 91 and 100% for added DL-serine and indole, respectively. Continuous production of L-tryptophan was also carried out using immobilized cells of E. coli and P. putida. The maximum concentration of L-tryptophan formed was 5.2 g liter-1 (99% molar yield for indole), and the concentration decreased to 4.2 g liter-1 after continuous operation for 20 days.
authors.affiliation: Central Research Institute, Mitsui Toatsu Chemicals Inc., Yokohama, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ishiwata
authors.forename: N
authors.initials: N
authors.lastname: Fukuhara
authors.forename: M
authors.initials: M
authors.lastname: Shimada
authors.forename: N
authors.initials: N
authors.lastname: Makiguchi
authors.forename: K
authors.initials: K
authors.lastname: Soda
mesh_terms: D000591:Amino Acid Isomerases / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007211:Indoles / Q000378:metabolism*; D011549:Pseudomonas / Q000201:enzymology; D012694:Serine / Q000378:metabolism*; D014364:Tryptophan / Q000096:biosynthesis*; D014367:Tryptophan Synthase / Q000378:metabolism*
chemical_list: D007211:Indoles; D012694:Serine; C030374:indole; D014364:Tryptophan; D014367:Tryptophan Synthase; D000591:Amino Acid Isomerases