Hydroxynitrile lyase catalyzed cyanohydrin synthesis at high pH-values.
The application of unusual high pH-values within enzymatic cyanohydrin synthesis has been investigated. Usually enzymatic cyanohydrin synthesis in two-phase systems requires low pH-values within the aqueous phase to suppress the non-enzymatic side reaction. In contrast, we investigated the usage of pH-values above pH 6 by using the highly enantioselective (S)-selective hydroxynitrile lyase from Manihot esculenta. With these unusual reaction conditions also the unfavorable substrate 3-phenoxy-benzaldehyde can be converted by the wild type enzyme with excellent conversion and enantiomeric excess yielding pure (S)-3-phenoxy-benzaldehyde cyanohydrin with an enantiomeric excess of 97%. Although the variant MeHNL-W128A shows a higher activity with respect to this reaction, the enantioselectivity was reduced (85% e.e.(S)). Additionally, a new continuous spectroscopic cyanohydrin assay monitoring the formation of 3-phenoxy-benzaldehyde cyanohydrin was developed.
von Langermann
Jan
J
Institut für Chemie, Universität Rostock, Albert-Einstein-Str. 3a, 18059 Rostock, Germany. jan.langermann@uni-rostock.de
Guterl
Jan-Karl
JK
Pohl
Martina
M
Wajant
Harald
H
Kragl
Udo
U
D000446:Aldehyde-Lyases / Q000737:chemistry*; D001547:Benzaldehydes / Q000737:chemistry; D001665:Binding Sites; D001709:Biotechnology / Q000379:methods*; D002384:Catalysis; D002621:Chemistry / Q000379:methods*; D004798:Enzymes / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D002365:Manihot / Q000201:enzymology; D008956:Models, Chemical; D009570:Nitriles / Q000737:chemistry*; D013379:Substrate Specificity; D013997:Time Factors
D001547:Benzaldehydes; D004798:Enzymes; D009570:Nitriles; C430593:cyanohydrin; C064808:3-phenoxybenzaldehyde; D000446:Aldehyde-Lyases; C079359:hydroxymandelonitrile lyase