title: Ethylene formation by cell-free extracts of Escherichia coli.
abstract: The pathway leading to the formation of ethylene as a secondary metabolite from methionine by Escherichia coli strain B SPAO has been investigated. Methionine was converted to 2-oxo-4-methylthiobutyric acid (KMBA) by a soluble transaminase enzyme. 2-Hydroxy-4-methylthiobutyric acid (HMBA) was also a product, but is probably not an intermediate in the ethylene-forming pathway. KMBA was converted to ethylene, methanethiol and probably carbon dioxide by a soluble enzyme system requiring the presence of NAD(P)H, Fe3+ chelated to EDTA, and oxygen. In the absence of added NAD(P)H, ethylene formation by cell-free extracts from KMBA was stimulated by glucose. The transaminase enzyme may allow the amino group to be salvaged from methionine as a source of nitrogen for growth. As in the plant system, ethylene produced by E. coli was derived from the C-3 and C-4 atoms of methionine, but the pathway of formation was different. It seems possible that ethylene production by bacteria might generally occur via the route seen in E. coli.
mesh_terms: D004926:Escherichia coli / Q000201:enzymology / Q000378:metabolism*; D005030:Ethylenes / Q000096:biosynthesis*; D008715:Methionine / Q000378:metabolism; D000637:Transaminases / Q000378:metabolism
chemical_list: D005030:Ethylenes; D008715:Methionine; D000637:Transaminases