抄録
cis-trans Isomerization of 3-(5-nitro-2-furyl)-2-(2-furyl)-acrylamide(AF-2) using Escherichia coli B/r and its two 5-nitro-2-furaldehyde semicarbazone(nitrofurazone)-resistant mutants was investigated. The isomerizing activity was detected in all three strains and markedly increased with acquiring resistance to nitro-furazone in intact cells and cell free extracts. Two distinct isomerases, nicotinamide adenine dinucleotide phosphate(NADPH)-dependent one with high activity and NAD(P)H-dependent with low activity were separate by sephadex G-100 and Sepharose 4B columns. Both enzyme activities agreed with the nitrofurazone-reducing activity due to O2-sensitive nitroreductase as reported previously. Another nitroreductase, 02-insensitive one, was unable to isomerize cis AF-2 to trans form. These results suggest that bacterial cis-trans isomerases are not O2-insensitive nitroreductase, but O2-sensitive ones.
