Exploration and utilization of novel aldoxime, nitrile, and nitro compounds metabolizing enzymes from plants and arthropods

Abstract

Aldoxime (R1R2C=NOH) and nitrile (R−C≡N) are nitrogen-containing compounds that are found in species representing all kingdoms of life. The enzymes discovered from the microbial “aldoxime-nitrile” pathway (aldoxime dehydratase, nitrile hydratase, amidase, and nitrilase) have been thoroughly studied because of their industrial importance. Although plants utilize cytochrome P450 monooxygenases to produce aldoxime and nitrile, many biosynthetic pathways are yet to be studied. Cyanogenic millipedes accumulate various nitrile compounds, such as mandelonitrile. However, no such aldoxime- and nitrile-metabolizing enzymes have been identified in millipedes. Here, I review the exploration of novel enzymes from plants and millipedes with characteristics distinct from those of microbial enzymes, the catalysis of industrially useful reactions, and applications of these enzymes for nitrile compound production.

Mandelonitrile lyase MDL2-mediated regulation of seed amygdalin and oil accumulation of Prunus Sibirica

“…In bioactivation process, amygdalin is hydrolyzed to form mandelonitrile by amygdalin hydrolase (AH) and prunasin hydrolase (PH) [ 27 , 31 – 33 ], and then hydrolyzed by mandelonitrile lyase (MDL) to form benzaldehyde with release of HCN [ 34 ]. Several plants have evolved various different detoxification mechanisms, with the most effective pathway that is the conversion of HCN into β-cyanoalanine by β-cyanoalanine synthase (β-CAS), and then hydrated by nitrilases (NITs) to generate asparagine or aspartate along with ammonia [ 2 , 27 , 35 ]. All these indicated that mandelonitrile was one key intermediate for both biosynthesis and bioactivation of amygdalin involved in several regulatory enzymes.…”