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B6db references: enzmichtech1

type Journal Article
authors Xu, H.; Wei, P.; Zhou, H.; Fan, W.; Ouyang, P.
title Efficient production of L-phenylalanine catalyzed by a coupled enzymatic system of transaminase and aspartase
journal Enz Microb Technol
Activity 2.6.1.70
sel selected
ui enzmichtech1
year (2003)
volume 5
pages 537-543
 
abstract A process for efficient production of L-phenylalanine catalyzed by a coupled enzymatic system of transaminase and aspartase with two organisms was developed. One strain, Escherichia coli EP8-10 produces significant transaminase and less aspartase under incubation in the glucose–beef extract medium. In the presence of 50 mg/ml cells of EP8-10, 0.24 mol/l phenylpyruvic acid (PPA) was converted to -phenylalanine (L-Phe) in 8 h with L-aspartic acid as an amine donor, the conversion rate was 97%. Another strain, E. coli EA-1, a mutant strain of ATCC11303, produces significant aspartase and less transaminase. -Aspartate (L-Asp), the amine donor, could be produced by EA-1 from fumarate (Fu) and ammonia. In presence of the mixture of EP8-10 and EA-1 cell, L-phenylalanine was efficiently produced from PPA and ammonium fumarate. An optimum reaction condition of the coupled enzymatic system is as follows: the concentration ratio of two cells as 0.4:1 (EA-1 to EP8-10), concentration ratio of two substrates (PPA to Fu) as 1:1.2 (mol). When concentration of PPA was 0.24, 0.233 mol/l (38 g/l), L-phenylalanine acid was accumulated by the conversion rate up to 97%. L-Phenylalanine production is more economical by the coupled enzymatic system, since one of the substrates L-aspartate was replaced by the relative cheap fumaric acid.
last changed 2007/12/10 20:22

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