Hevea brasiliensis HbHNL

Until 1987, the (R)-PaHNL from almonds was the only HNL used as catalyst in the enantioselective preparation of cyanohydrins. Therefore, it was of great interest to get access to HNLs which catalyze the formation of (5 )-cyanohydrins. (5 )-SbHNL [EC 4.1.2.11], isolated from Sorghum bicolor, was the first HNL used for the preparation of (5 )-cyanohydrins. Since the substrate range of SbHNL is limited to aromatic and heteroaromatic aldehydes as substrates, other enzymes with (5 )-cyanoglycosides have been investigated as catalysts for the synthesis of (5 )-cyanohydrins. The (5 )-HNLs from cassava (Manihot esculenta, MeHNL) and from Hevea brasiliensis (HbHNL) proved to be highly promising candidates for the preparation of (5 )-cyanohydrins. Both MeHNL and HbHNL have been overexpressed successfully in Escherichia coli, Saccharomyces cerevisiae and Pichia pastoris. 

Scheme 4.107 Enzymatic cyanohydrin formation catalyzed by HNL [429] (MTBE methyl-tert-butyl ether (R)-PaHNL (R)-hydroxynitrile lyase originating from Primus amygdalus (S)-HbHNL (S)-hydroxynitrile lyase originating from Hevea brasiliensis).

HbHNL Hevea brasiliensis (rubber tree) Aliphatic/aromatic/heteroaromatic/a,p-unsaturated (S)... 

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