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Stereoselective synthesis of l-homophenylalanine using the carbamoylase method with in situ racemization viaN-acylamino acid racemase

Paper ID Volume ID Publish Year Pages File Format Full-Text
35989 45117 2007 7 PDF Available
Title
Stereoselective synthesis of l-homophenylalanine using the carbamoylase method with in situ racemization viaN-acylamino acid racemase
Abstract

N-Acylamino acid racemase (NAAAR) gene of Deinococcus radiodurans BCRC12827 was cloned into expression vector pQE30 to generate pQE-naaar and expressed in recombinant Escherichia coli JM109. The expressed enzyme purified from the crude cell extract of IPTG-induced E. coli JM109 (pQE-naaar) exhibited high racemization activity to N-carbamoyl-l-homophenylalanine (NCa-l-HPA) and N-carbamoyl-d-homophenylalanine (NCa-d-HPA) with specific activities of 1.91 U/mg protein and 1.31 U/mg protein, respectively. To develop a recombinant E. coli whole cell system for the conversion of racemic NCa-HPA to l-homophenylalanine (l-HPA), naaar gene from D. radiodurans and l-N-carbamoylase (LNCA) gene from Bacillus kaustophilus BCRC11223 were cloned and coexpressed in E. coli cells. Recombinant cells treated with 0.5% toluene at 30 °C for 30 min exhibited enhanced NAAAR and LNCA activities, which are about 20- and 60-fold, respectively, higher than those of untreated cells. Using toluene-permeabilized recombinant E. coli cells, a maximal productivity of 7.5 mmol l-HPA/l h with more than 99% yield could be obtained from 150 mmol racemic NCa-HPA. Permeabilized cells also showed considerable stability in the bioconversion process using 10 mmol racemic NCa-HPA as substrate, no significantly decrease in conversion yield for l-HPA was found in the eight cycles.

Keywords
Angiotensin-converting enzyme inhibitor; l-Homophenylalanine; N-Acylamino acid racemase; l-N-Carbamoylase; Permeabilized cell; Bioconversion
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Stereoselective synthesis of l-homophenylalanine using the carbamoylase method with in situ racemization viaN-acylamino acid racemase
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Publisher
Database: Elsevier - ScienceDirect
Journal: Process Biochemistry - Volume 42, Issue 5, May 2007, Pages 856–862
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us