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Int. J. Mol. Sci. 2009, 10(6), 2578-2590; doi:10.3390/ijms10062578
Article

Tryptophanase-Catalyzed L-Tryptophan Synthesis from D-Serine in the Presence of Diammonium Hydrogen Phosphate

1,* , 1, 2 and 2
Received: 21 May 2009; Accepted: 1 June 2009 / Published: 3 June 2009
(This article belongs to the Special Issue Origin of Life)
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Abstract: Tryptophanase, an enzyme with extreme absolute stereospecificity for optically active stereoisomers, catalyzes the synthesis of L-tryptophan from L-serine and indole through a β-substitution mechanism of the ping-pong type, and has no activity on D-serine. We previously reported that tryptophanase changed its stereospecificity to degrade D-tryptophan in highly concentrated diammonium hydrogen phosphate, (NH4)2HPO4 solution. The present study provided the same stereospecific change seen in the D-tryptophan degradation reaction also occurs in tryptophan synthesis from D-serine. Tryptophanase became active to D-serine to synthesize L-tryptophan in the presence of diammonium hydrogen phosphate. This reaction has never been reported before. D-serine seems to undergo β-replacement via an enzyme-bonded α-aminoacylate intermediate to yield L-tryptophan.
Keywords: tryptophanase; diammonium hydrogen phosphate; D-serine; tryptophan synthesis; stereospecific change tryptophanase; diammonium hydrogen phosphate; D-serine; tryptophan synthesis; stereospecific change
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Shimada, A.; Ozaki, H.; Saito, T.; Noriko, F. Tryptophanase-Catalyzed L-Tryptophan Synthesis from D-Serine in the Presence of Diammonium Hydrogen Phosphate. Int. J. Mol. Sci. 2009, 10, 2578-2590.

AMA Style

Shimada A, Ozaki H, Saito T, Noriko F. Tryptophanase-Catalyzed L-Tryptophan Synthesis from D-Serine in the Presence of Diammonium Hydrogen Phosphate. International Journal of Molecular Sciences. 2009; 10(6):2578-2590.

Chicago/Turabian Style

Shimada, Akihiko; Ozaki, Haruka; Saito, Takeshi; Noriko, Fujii. 2009. "Tryptophanase-Catalyzed L-Tryptophan Synthesis from D-Serine in the Presence of Diammonium Hydrogen Phosphate." Int. J. Mol. Sci. 10, no. 6: 2578-2590.


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