title: A transplasma membrane redox system in Phycomyces blakesleeanus: properties of a ferricyanide reductase activity regulated by iron level and vitamin K3.
abstract: Intact Phycomyces blaskesleeanus mycelia are capable of reducing extracellular ferricyanide and this transmembrane reduction is an enzymatic process, which is enhanced by the presence of 10 mM lactate. It is modulated in response to intracellular iron levels and negatively regulated by iron and copper. It is inhibited by NEM, p CMB, iodoacetate, Zn2+, Cd2+, dicumarol, and capsaicine analog, but not by cloroquine, and activated by Ca2+, Mg2+, Na+, and K+. Ferricyanide reduction was concomitant with proton release into the extracellular medium, both processes being greatly promoted by vitamin K3 following hyperbolic saturation kinetics with regard to ferricyanide concentration. No stoichiometric proton release was observed with regard to ferricyanide reduction in the absence or the presence of vitamin K3. Proton release coupled with ferricyanide reductase activity does not appear to be due to H+-ATPase. The relevance of these findings to the relationship between the two processes is discussed.
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Universidad de León, León, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Baroja-Mazo
authors.forename: Pilar
authors.initials: P
authors.lastname: Del Valle
authors.forename: Javier
authors.initials: J
authors.lastname: Rúa
authors.forename: Félix
authors.initials: F
authors.lastname: Busto
authors.forename: Sergio
authors.initials: S
authors.lastname: De Cima
authors.forename: Dolores
authors.initials: D
authors.lastname: De Arriaga
mesh_terms: D002462:Cell Membrane / Q000378:metabolism*; D005292:Ferricyanides / Q000493:pharmacokinetics*; D007501:Iron / Q000378:metabolism*; D008657:Metabolic Clearance Rate; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D010084:Oxidation-Reduction; D010800:Phycomyces / Q000378:metabolism*; D024483:Vitamin K 3 / Q000378:metabolism*
chemical_list: D005292:Ferricyanides; C007931:hexacyanoferrate III; D024483:Vitamin K 3; D007501:Iron; D009247:NADH, NADPH Oxidoreductases; C014227:ferricyanide reductase