Hydratase gene

A recombinant Escherichia coli strain containing the cloned limonene hydratase gene was able to grow in a water-limonene two-phase system and converted limonene to a-terpineol [36], Limonene, a cost-effective and readily available monoterpene, served both as the substrate and the neat solvent for the production of a-terpineol. 

Sexton, A.C. and Howlett, B.J. 2000. Characterization of a cyanide hydratase gene in the phy-topaihog dicfxmgvis Leptosphaeria maculans. Gene, 263 463-470. 

Wang, P. and Van Etten, H.D. 1992. Cloning and properties of a cyanide hydratase gene from the phytopathogenic fungus Gloeocercospora sorghi. Biochemical and Biophysical Research Communications, 187 1048-54. 

Yamaki, T., Oikawa, T., Ito, K., et al. 1997. Cloning and sequencing of a nitrile hydratase gene from Pseudonocardia thermophila JCM3095. Journal of Fermentation and Bioengineering, 83 474-7. 

With both these strains, the enzymatic system is composed of nitrile hydratases and amidases. The nitrile hydratase gene of Brevibacterium R312 is cloned, sequenced (ref. 17) and over expressed in Rhodococcus rhodochrous ATCC12674 (pKRNH2) (ref. 18). The best selectivity which can be hoped for with this nitrile hydratase is 93 % (ref. 4). Moreover, the cyanovaleramide with its poor solubility must not be accumulated and requires a biocatalyst with a superactivated amidase activity. The nitrile hydratase is less stable than amidase and the biocatalyst with these two enzymes would not be sufficiently robust for an industrial application. 

TsugeT, FukuiT, Matsusaki H, Taguchi S.Kobayashi G, Ishizaki A, et al. Molecular cloning of two (R)-specific enoyl-CoA hydratase genes from Pseudomonas aeruginosa and their use for polyhydroxyalkanoate biosynthesis. FEMS Microbiol Lett 2000 184 193-8. 

Further, E. coli cells expressing the cyanide hydratases genes from A. niger and P, chrysogenum were found to exhibit activities for both HCN and some nitrile compounds, preferably 2-cyanopyridine (1-3.6% relative activity compared to HCN) [6]. Dual nitrilase/cyanide hydratase activities were also described for the enzymes in Fusarium oxysporum and Fusarium lateritium [36, 37]. It is possible that this dual activity is a general feature of cyanide hydratases but has largely gone unnoticed. 

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