Hydroxynitrile recombinant

The hydroxynitrile lyase (HNL)-catalyzed addition of HCN to aldehydes is the most important synthesis of non-racemic cyanohydrins. Since now not only (f )-PaHNL from almonds is available in unlimited amounts, but the recombinant (S)-HNLs from cassava (MeHNL) and rubber tree (HbHNL) are also available in giga units, the large-scale productions of non-racemic cyanohydrins have become possible. The synthetic potential of chiral cyanohydrins for the stereoselective preparation of biologically active compounds has been developed during the last 15 years. 

Forster, S., Roos, J., Effenberger, F. et al. (1996) The first recombinant hydroxynitrile lyase and its application in the synthesis of (S)-cyanohydrins. Angewandte Chemie (International Edition in English), 35, 457 459. 

The detailed characterization of hydroxynitrile lyases from Sorghum hicolor (E.C. 4.1.2.11) and Linum usitassimum (E.C. 4.1.2.37) has been hampered for a long time due to the lack of a recombinant expression system. Therefore our studies were focused on cloning of the coding genes, recombinant expression, and characterization of these enzymes. 

HNLs comprise a heterogenous enzyme family, since hydroxynitrile lyase activity has evolved in different structural frames by convergent evolution [17, 18]. Thus, (S) -specific HNLs based on an a/P-hydrolase fold framework from Manihot esculmta (cassava) [19-21], Hevea hrasilensis (rubber tree) [22-26], and Sorghum hicolor (millet) [27-33] have been described. (R)-specific HNLs based on the structural framework of oxidoreductases were isolated from Linum usitatissimum (flax) [30, 34-37] and Rosaceae (e.g., bitter almonds) [31, 38]. Despite their potential in biocatalysis only few HNLs (from cassava and rubber tree) are available by recombinant gene expression, which is a prerequisite for their technical application [20, 24]. Thus, cloning, recombinant expression, and... 

A. (2012) Application of a recombinant Escherichia coli whole-cell catalyst expressing hydroxynitrile lyase and nitrilase activities in ionic liquids for the production of (S)-mandelic acid and (S)-mandeloamide. Adv. Synth. Catal., 354, 113-122. 

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