Millipede Catalyst
Swarms of this cyanide-secreting millipede have entered houses, writhed on railway tracks causing delays, and, in short, made themselves a nuisance in Japan, their host country. But Chamberlinius hualienensis, the arthropod native of Taiwan which invaded Okinawa Island in 1983, could soon become a source of catalysts in chemical factories.
Thanks to a group of enzymes called Hydroxynitrile lyases (HNLs), some plants and bacteria, which have reserves of cyanide-containing compounds, release hydrogen cyanide as defense chemicals. Chemists employ the enzyme for the reverse reaction, combining aldehydes with hydrogen cyanide to make cyanohydrins, which, in turn, serve as building blocks for specialty chemicals.
In the latest issue of the Proceedings of the National Academy of Sciences, scientists from Japan report that they have isolated a new member of the HNL family from the millipede, Chamberlinius hualienensis. With benzaldehyde as the starting material, they’ve made mandelonitrile, a cyanohydrin a precursor for pharmaceutical drugs.
The newest member of enzyme family proved to be a quicker catalyst compared to the industry favorite, the almond HNL. And greener too because the reaction uses less energy, needs no additional solvents, and leaves less hazardous waste at the end of reaction. Plus, this is not the only reaction it catalyzes – it was found to work with a variety of aromatic aldehydes. The enzyme is stable over a high range of temperatures and pH values.
“The primary structure of this HNL is so unique that no protein in the database is similar to this one,” says Dr. Yasuhisa Asano, an author of this paper. With the discovery of this industrial catalyst from an arthropod – believed to be a first – the researcher speculates that other members of the 5000-plus species rich family could be potential sources of next-generation biocatalysts.
What’s more, the researchers may have briefly halted the spread of these invasive millipedes. The enzyme for the early experiments came from pickings off a railway track. “For scale up, we would like to switch from millipede to microbiological technology,” says Asano. They’ve already succeeded in cloning and expressing the gene for the enzyme in yeasts.