title: An adaptable spectroelectrochemical titrator: the midpoint reduction potential of the iron-sulfur center in lysine 2,3-aminomutase.
abstract: Elaborations to an earlier design of an electron paramagnetic resonance (EPR) spectroelectrochemical titrator are described. While maintaining the anaerobic capabilities of the original design, a number of modifications and revisions have been introduced. The most significant modification is the use of a detachable spectral cell, making the apparatus modular and adaptable for multiple forms of spectroscopy. Additional modifications include removable reference, auxiliary, and working electrodes; modifications to facilitate sample transfer; and adaptations for operation within an anaerobic chamber. This apparatus has been used successfully in the coulometric titration of a [4Fe-4S] enzyme, as measured by EPR spectroscopy. The midpoint reduction potential for the 2+/1+ couple in the [4Fe-4S] cluster of lysine 2,3-aminomutase is -479+/-5mV, a value that falls within the range typical of ferredoxin-like iron-sulfur clusters.
authors.affiliation: Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 35726, USA.
authors.forename: Glen T
authors.initials: GT
authors.lastname: Hinckley
authors.forename: Perry A
authors.initials: PA
authors.lastname: Frey
mesh_terms: D000693:Anaerobiosis; D004566:Electrodes; D004578:Electron Spin Resonance Spectroscopy / Q000295:instrumentation*; D019751:Intramolecular Transferases / Q000737:chemistry* / Q000378:metabolism; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000378:metabolism; D010084:Oxidation-Reduction; D010269:Paraquat / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet
chemical_list: D007506:Iron-Sulfur Proteins; D019751:Intramolecular Transferases; C021518:lysine 2,3-aminomutase; D010269:Paraquat