BACKGROUND Studies performed within the last decade have indicated that microbial reduction of Fe(III) to Fe(II) is a biologically significant process. The ferric reductase (FeR) from Archaeoglobus fulgidus is the first reported archaeal ferric reductase and it catalyzes the flavin-mediated reduction of ferric iron complexes using NAD(P)H as the electron donor. Based on its catalytic activity, ...

The ligand-gated outer membrane porin FepA serves Escherichia coli as the receptor for the siderophore ferric enterobactin. We characterized the ability of seven analogs of enterobactin to supply iron via FepA by quantitatively measuring the binding and transport of their 59Fe complexes. The experiments refuted the idea that chirality of the iron complex affects its recognition by FepA and demo...

One of the difficulties in preparing accurate ambient-temperature model complexes for heme proteins, particularly in the ferric state, has been the generation of mixed-ligand adducts: complexes with different ligands on either side of the heme. The difference in the accessibility of the two sides of the heme in the H93G cavity mutant of myoglobin (Mb) provides a potential general solution to th...

The equilibrium constants for the tryptophan binding to indoleamine 2,3-dioxygenase, a protohemoprotein, in its ferric (Fe3+), ferrous (Fez+), and CO-bound (Fea+CO) forms were determined by the spectrophotometric titration method. All these enzyme derivatives showed marked spectral changes upon tryptophan binding. Such a spectral change for the ferric enzyme was, however, specific to the L isom...

Wastewater Treatment Facilities have been built to remove biological and chemical waste from water as it is used. These facilities maintain a healthy environment for organisms as well as people because it removes potentially harmful material and kills pathogens that would easily spread through cities. Phosphorus is a compound of interest because a high concentration of it at discharge will even...

FhuD is the periplasmic binding protein of the ferric hydroxamate transport system of Escherichia coli. FhuD was isolated and purified as a His-tag-labeled derivative on a Ni-chelate resin. The dissociation constants for ferric hydroxamates were estimated from the concentration-dependent decrease in the intrinsic fluorescence intensity of His-tag-FhuD and were found to be 0.4 microM for ferric ...

The magnitude and temperature-sensitivity of oxygen isotope fractionation in ferric oxide-water systems remain uncertain. In this study, three different synthetic methods are used to investigate the temperature dependence of the fractionation between water and hematite, akaganeite, and goethite at near-surface temperatures. Our results reveal two similarities among these ferric oxide-water syst...