An onion enzyme that makes the eyes water

Nature 419 (6908): 685
17 October 2002
doi:10.1038/419685a

S. Imai [1], N. Tsuge [1], M. Tomotake [1], Y. Nagatome [1], H. Sawada [1], T. Nagata [2] & H. Kumagai [3]

[1] Somatech Center, House Foods Corporation, Takanodai, Yotsukaido, Chiba 284-0033, Japan
[2] Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
[3] Division of Integrated Life Science, Graduate School of Biostudies, Kyoto University, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan

ABSTRACT The irritating lachrymatory factor that is released by onions when they are chopped up has been presumed to be produced spontaneously following the action of the enzyme alliinase, which operates in the biochemical pathway that produces the compounds responsible for the onion's characteristic flavour. Here we show that this factor is not formed as a by-product of this reaction, but that it is specifically synthesized by a previously undiscovered enzyme, lachrymatory-factor synthase. It may be possible to develop a non-lachrymatory onion that still retains its characteristic flavour and high nutritional value by downregulating the activity of this synthase enzyme.

http://www.nature.com/nature/journal/v419/n6908/abs/419685a.html