Mini-Review: Recent Developments in Hydroxynitrile Lyases for Industrial Biotechnology

Abstract

Hydroxynitrile lyases (HNLs) catalyze the cleavage as well as the formation of cyanohydrins. The latter reaction is valuable for the stereoselective C-C bond formation by condensation of HCN with carbonyl compounds. The resulting cyanohydrins serve as versatile building blocks for a broad range of chemical and enzymatic follow-up reactions. A significant number of (R)- and (S)-selective HNLs are known today and the number is still increasing. HNLs not only exhibit varying substrate scope but also differ in sequence and structure. Tailor-made enzymes for large-scale manufacturing of cyanohydrins with improved yield and enantiomeric excess are very interesting targets, which is reflected in a solid number of patents. This review will complement and extend our recent review with a strong focus on applications of HNLs for the synthesis of highly functionalized, chiral compounds with newest literature, recent and current patent literature.

Enzyme discovery beyond homology: a unique hydroxynitrile lyase in the Bet v1 superfamily

“…They can perform the reverse condensation reaction (carbon-carbon bond formation), and synthesize α-cyanohydrins in a stereospecific manner. Cyanohydrins are building blocks for a number of follow-up reactions, and the products find application in agrochemical, pharmaceutical and cosmetic industries78910. Although ( R )- and ( S )-selective HNLs are exploited in biocatalysis, new enzymes with outstanding characteristics are constantly sought for.…”

Enantioselective synthesis of cyanohydrins catalysed by hydroxynitrile lyases – a review

“…4,51 Industrially the handling of such toxic compounds and in particular of HCN is no problem and consequently HNLs are the catalyst of choice in industry. [7][8][9]15,[20][21][22] Various reviews concentrate on all aspects of catalyst preparation, modification and mechanisms, including the enantioselectivity and its modification in HNLs; 4,6 similar reviews exist for chemical catalysts. 2,23,24 While HNL immobilisation for reaction engineering has recently been reviewed, 7 we herein introduce the asymmetric synthesis catalysed by HNLs and the essential background information for their successful application.…”

Production of Hydroxynitrile Lyase from Davallia tyermannii (DtHNL) in Komagataella phaffii and Its Immobilization as a CLEA to Generate a Robust Biocatalyst

“…HNLs find applications in biocatalysis due to their ability to synthesize enantiomerically pure α‐cyanohydrins, which are key building blocks for pharmaceuticals and agrochemicals. The introduction of a nitrile group into the molecule provides the possibility for a variety of modifications on both the nitrile and the hydroxy group, and allows chemical or chemoenzymatic follow‐up reactions . Several functional group transformations can be performed on cyanohydrins .…”