📅  最后修改于: 2022-03-11 14:55:44.457000             🧑  作者: Mango
Onions produce the chemical irritant known as syn-propanethial-S-oxide.
It stimulates the eyes' lachrymal glands so they release tears. The
synthase enzyme converts the amino acids sulfoxides of the onion into
sulfenic acid. The unstable sulfenic acid rearranges itself into
syn-ropanethial-S-oxide.