FIG 6.

Ferroxidase activity of ceruloplasmin (CP) in urine. (A) The optical density at 562 nm (OD₅₆₂) of Fe²⁺-ferrozine complex formation in urine with or without CP and apotransferrin (aTFN) was measured. ****, P < 0.0001; ANOVA with Dunnett's posttest. (B) Representative image of CP- and aTFN-dependent decrease in Fe²⁺ iron availability, as determined by complex formation with ferrozine. 1, urine alone; 2, FeSO₄; 3, FeSO₄ and CP; 4, FeSO₄, CP, and aTFN. (C) Expression of iutA in UPEC strain CFT073 cultured with or without the indicated concentration of CP in healthy human urine was determined by qPCR after normalization to gapA. **, P < 0.01; t test (n = 3, in duplicate). The mean and standard error of the mean are presented.