title: Ecdysone 3-epimerase from the midgut of Manduca sexta (L.).
abstract: Ecdysone 3-epimerase was partially purified by ammonium sulfate fractionation from the 100,000 g supernate of Manduca sexta midguts. The enzyme converts ecdysone and 20-hydroxyecdysone to their respective 3-epimers, requires NADH or NADPH and O2 for this reaction, and has the following kinetic parameters: for ecdysone, Km = 17.0 +/- 1.4 microM, Vmax = 110.6 +/- 14.6 pmol min-1 mg-1; for 20-hydroxyecdysone, Km = 47.3 +/- 7.5 microM, Vmax = 131.0 +/- 3.5 pmol min-1 mg-1: for NADPH, Km = 85.4 +/- 10.6 microM; for NADH, Km = 51.3 +/- 1.3 microM. The reaction is irreversible and can be inhibited by various ecdysteroids.
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004440:Ecdysone; D007422:Intestines / Q000201:enzymology*; D007535:Isomerases / Q000302:isolation & purification*; D007915:Lepidoptera / Q000201:enzymology*; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D013251:Steroid Isomerases / Q000037:antagonists & inhibitors / Q000302:isolation & purification*
chemical_list: D009243:NAD; D004440:Ecdysone; D009249:NADP; D007535:Isomerases; D013251:Steroid Isomerases; C022756:ecdysone 3-epimerase