An onion enzyme that makes the eyes water

An onion enzyme that makes the eyes water

2002

A:PS

The production of lachrymatory-factor (an eye-irritating substance emitted when onions are chopped up) in a crude preparation containing onion alliinase [alliin lyase] and 1-propenyl-L-cysteine sulphoxide (PRENSCO) was investigated. The analysis of the complete cDNA sequence of three proteins detected in the preparation revealed a gene encoding a new enzyme, here designated as lachrymatory-factor synthase. The enzyme showed high substrate specificity, producing lachrymatory factor from only trans-PRENSCO, which is the naturally occurring form in onion. Lachrymatory factor was detected only when purified alliinase, PRENSCO, and lachrymatory-factor synthase were present in the reaction mixture. The omission of the synthase from the reaction mixture resulted in an increase yield of thiosulfinate, the condensation product of 1-propenyl-sulphenic acid. The results indicate that it might be possible to develop a non-lachrymatory onion by suppressing the lachrymatory-factor synthase gene while increasing thiosulfinate yield.

v.419:6908, NATURE

Research > Published Articles