Characterization of iron-sulfur clusters in lysine 2,3-aminomutase by electron paramagnetic resonance spectroscopy.
Lysine 2,3-aminomutase from Clostridia catalyzes the interconversion of L-alpha-lysine with L-beta-lysine. The purified enzyme contains iron-sulfur ([Fe-S]) clusters, pyridoxal phosphate, and Co(II) [Petrovich, R. M., Ruzicka, F. J., Reed, G. H., & Frey, P. A. (1991) J. Biol. Chem. 266, 7656-7660]. Enzymatic activity depends upon the presence and integrity of these cofactors. In addition, the enzyme is activated by S-adenosylmethionine, which participates in the transfer of a substrate hydrogen atom between carbon-3 of lysine and carbon-2 of beta-lysine [Moss, M., & Frey, P. A. (1987) J. Biol. Chem. 262, 14859-14862]. This paper describes the electron paramagnetic resonance (EPR) properties of the [Fe-S] clusters. Purified samples of the enzyme also contain low and variable levels of a stable radical. The radical spectrum is centered at g = 2.006 and is subject to inhomogeneous broadening at 10 K, with a p1/2 value of 550 +/- 100 microW. The low-temperature EPR spectrum of the [Fe-S] cluster is centered at g = 2.007 and undergoes power saturation at 10 K in a homogeneous manner, with a p1/2 of 15 +/- 2 mW. The signals are consistent with the formulation [4Fe-4S] and are adequately simulated by a rhombic spectrum, in which gxx = 2.027, gyy = 2.007, and gzz = 1.99. Treatment of the enzyme with reducing agents converts the cluster into an EPR-silent form. Oxidation of the purified enzyme by air or ferricyanide converts the [Fe-S] complex into a species with an EPR spectrum that is consistent with the formulation [3Fe-4S].(ABSTRACT TRUNCATED AT 250 WORDS)
Petrovich
R M
RM
Institute of Enzyme Research, Graduate School, University of Wisconsin, Madison 53705.
Ruzicka
F J
FJ
Reed
G H
GH
Frey
P A
PA
D000591:Amino Acid Isomerases / Q000737:chemistry* / Q000378:metabolism; D004227:Dithionite / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D004789:Enzyme Activation; D005292:Ferricyanides / Q000494:pharmacology; D005609:Free Radicals; D019751:Intramolecular Transferases; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000378:metabolism; D046911:Macromolecular Substances; D010084:Oxidation-Reduction
D005292:Ferricyanides; D005609:Free Radicals; D007506:Iron-Sulfur Proteins; D046911:Macromolecular Substances; C007931:hexacyanoferrate III; D004227:Dithionite; D000591:Amino Acid Isomerases; D019751:Intramolecular Transferases; C021518:lysine 2,3-aminomutase