Popis: |
Properties of Pichia guilliermondii ferrireductase of the crude extracts and ammonium sulfate preparations were studied. NADH and Cu (II) ions are necessary for ferrireductase activity. Mg (II) also stimulates this reaction while oxygen acts as a slight inhibitor. Ferrireductase reduces Fe (III) in complex with citrate, iron-binding peptide from the culture medium of P. guilliermondii, rhodotorulic acid, coprogen, desferrioxamine B and EDTA. Mutants rib80, rib81 and hit of Pichia guilliermondii that have damaged system of riboflavin biosynthesis and iron transport regulation are characterized by high ferrireductase activity. Iron through negative feed-back mechanism regulates activity of ferrireductase synthesis in P. guilliermondii, Candida famata, Candida krusei, Candida boidinii, but not in Pichia pinus and Hansenula polymorpha. |