NADH promotes iron release from a siderophore through reduction

INOR 46

Kassy A. Mies, miesk@meredith.edu, Department of Chemistry, Physics, and Geoscience, Meredith College, 3800 Hillsborough St., Raleigh, NC 27607 and A. L. Crumbliss, alc@chem.duke.edu, Department of Chemistry, Duke University, Box 90346, Durham, NC 27708-0346.
We have previously shown that the release of iron from a siderophore, ferrioxamine B, can be facilitated by reduction if a suitable ternary complex is formed. Here we demonstrate that in addition to the naturally occurring reducing agents ascorbate and glutathione, NADH is also capable of reducing a siderophore-ternary complex. Evidence is provided which shows that NADH is capable of reducing ferrioxamine B directly in a physiologically relevant pH range. This direct reduction of ferrioxamine B by NADH is rapid in comparison to the reduction of the siderophore-ternary complex by any of the reducing agents that have been studied. Iron release, however, is only facilitated when an iron(II) chelator is present to sequester the iron(II) and prevent re-oxidation. Thus, in vivo, direct siderophore reduction is a viable mechanism for iron release and the presence or absence of a suitable iron(II) chelator may act to regulate that release.
 

General Inorganic Chemistry
9:00 AM-1:00 PM, Sunday, April 6, 2008 Morial Convention Center -- Rm. 219, Oral

Division of Inorganic Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008