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Protein engineering on biphenyl dioxygenase for conferring activity to convert 7-hydroxyflavone and 5,7-dihydroxyflavone (chrysin)

Paper ID Volume ID Publish Year Pages File Format Full-Text
21649 43233 2008 7 PDF Available
Title
Protein engineering on biphenyl dioxygenase for conferring activity to convert 7-hydroxyflavone and 5,7-dihydroxyflavone (chrysin)
Abstract

A central part (amino-acid position 268–397 of 458 amino-acid residues) of the biphenyl dioxygenase large (α) subunit, BphA1, from Pseudomonas pseudoalcaligenes strain KF707 was exchanged with the corresponding part of BphA1 from another biphenyl-degrading bacterium, Pseudomonas putida strain KF715, to construct hybrid BphA1, BphA1 (715-707). When expressed in Escherichia coli together with the bphA2A3A4BC genes from strain KF707, this enzyme was shown to possess activity for degrading both 1-phenylnaphthalene and 2-phenylnaphthalene. Between central parts of BphA1 from strains KF707 and KF715, the difference of amino-acid residues resided only in position 324–325. An attempt was made to improve the substrate preference of BphA1 by applying random amino-acid substitutions at these positions to BphA1 (715-707). After screening the mutant library to bioconvert several flavonoids, BphA1 (1-22; T324A and I325L) and BphA1 (2-2; T324L and I325I) were selected. When expressed in E. coli together with bphA2A3A4B from strain KF707, both BphA1 (1-22) and BphA1 (2-2) bioconverted the refractory flavonoids, 7-hydroxyflavone and 5,7-dihydroxyflavone (chrysin), which were hardly converted by any unmodified and artificially-modified shuffled biphenyl dioxygeneses, into their vicinal diol forms, i.e., 2-(2,3-dihydroxyphenyl)-7-hydroxy-chromen-4-one and 2-(2,3-dihydroxyphenyl)-5,7-dihydroxy-chromen-4-one, respectively. In addition, trans-chalcone was converted into 3-(2,3-dihydroxyphenyl)-1-phenylpropan-1-one and further into 1,3-bis-(2,3-dihydroxyphenyl)-propan-1-one. The antioxidative activity of these generated compounds was markedly higher than that of the original substrates used.

Keywords
chalcone; 7-hydroxyflavone; chrysin; biphenyl dioxygenase; dihydrodiol dehydrogenase
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Protein engineering on biphenyl dioxygenase for conferring activity to convert 7-hydroxyflavone and 5,7-dihydroxyflavone (chrysin)
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Bioscience and Bioengineering - Volume 106, Issue 2, August 2008, Pages 121–127
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