Self-association of adrenodoxin studied by using analytical ultracentrifugation

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Item Type:	Article
Title:	Self-association of adrenodoxin studied by using analytical ultracentrifugation
Creators Name:	Behlke, J., Ristau, O., Mueller, E.C., Hannemann, F. and Bernhardt, R.
Abstract:	The mitochondrial steroid hydroxylase system of vertebrates utilizes adrenodoxin (Adx), a small iron-sulfur cluster protein of about 14 kDa as an electron carrier between a reductase and cytochrome P450. Although the crystal structure of this protein has been elucidated, the solution structure of Adx was discussed contrary in the literature [I.A. Pikuleva, K. Tesh, M.R. Waterman, Y. Kim, The tertiary structure of full-length bovine adrenodoxin suggests functional dimers, Arch. Biochem. Biophys. 373 (2000) 44-55; D. Beilke, R. Weiss, F. Lohr, P. Pristovsek, F. Hannemann, R. Bernhardt, H. Ruterjans, A new electron mechanism in mitochondrial steroid hydroxylase systems based on structural changes upon the reduction of adrenodoxin, Biochemistry 41 (2002) 7969-7978]. Therefore, it was necessary to study the self-association of this protein by using analytical ultracentrifugation over a larger concentration range. As could be demonstrated in sedimentation velocity experiments, as well as sedimentation equilibrium runs with explicit consideration of thermodynamic non-ideality, the full-length protein (residues 1-128) in the oxidized state resulted in a monomer-dimer equilibrium (K(a)~3x10(2) M(-1)). For truncated Adx (1-108), as well as the reduced Adx, the association behavior was strongly reduced. The consequences of this behavior are discussed with respect to the physiological meaning for the Adx system.
Keywords:	Sedimentation Velocity, Sedimentation Equilibrium, Self-Association, Association Constants, Thermodynamic Non-Ideality
Source:	Biophysical Chemistry
ISSN:	0301-4622
Publisher:	Elsevier
Volume:	125
Number:	1
Page Range:	159-165
Date:	January 2007
Official Publication:	https://doi.org/10.1016/j.bpc.2006.07.011
PubMed:	View item in PubMed

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