Biophysical Journal 71: 858-867 (1996)
© 1996 the Biophysical Society

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Salamon, Z Articles by Tollin, G Search for Related Content PubMed PubMed Citation Articles by Salamon, Z Articles by Tollin, G

Surface plasmon resonance studies of complex formation between cytochrome c and bovine cytochrome c oxidase incorporated into a supported planar lipid bilayer. II. Binding of cytochrome c to oxidase-containing cardiolipin/phosphatidylcholine membranes.

Department of Biochemistry, University of Arizona, Tucson 85721, USA.

ABSTRACT

Complex formation between horse heart cytochrome c (cyt c) and bovine cytochrome c oxidase (cco) incorporated into a supported planar egg phosphatidylcholine membrane containing varying amounts of cardiolipin (CL) (0-20 mol%) has been studied under low (10 mM) and medium (160 mM) ionic strength conditions by surface plasmon resonance (SPR) spectroscopy. Both specific and nonspecific modes of cyt c binding are observed. The dissociation constant of the specific interaction between cyt c and cco increases from approximately 6.5 microM at low ionic strength to 18 microM at medium ionic strength, whereas the final saturation level of bound protein is independent of salt concentration and corresponds to approximately 53% of the total cco molecules present in the membrane. This suggests a 1:1 binding stoichiometry between the two proteins. The nonspecific binding component is governed by electrostatic interactions between cyt c and the membrane lipids and results in a partially ionic strength-reversible protein-membrane association. Thus, hydrophobic interactions between cyt c and the membrane, which are the predominant mode of binding in the absence of cco, are greatly suppressed. Both the amount of nonspecifically bound protein and the binding affinity can be varied over a broad range by changing the ionic strength and the extent of CL incorporation into the membrane. Under conditions approximating the physiological state in the mitochondrion (i.e., 20 mol% CL and medium ionic strength), 1-1.5 cyt c molecules are bound to the lipid phase per molecule of cco, with a dissociation constant of 0.1 microM. The possible physiological significance of these observations is discussed.

This article has been cited by other articles:

				S. Bernad, S. Oellerich, T. Soulimane, S. Noinville, M.-H. Baron, M. Paternostre, and S. Lecomte Interaction of Horse Heart and Thermus thermophilus Type c Cytochromes with Phospholipid Vesicles and Hydrophobic Surfaces Biophys. J., June 1, 2004; 86(6): 3863 - 3872. [Abstract] [Full Text] [PDF]

				M. Suter, C. Reme, C. Grimm, A. Wenzel, M. Jaattela, P. Esser, N. Kociok, M. Leist, and C. Richter Age-related Macular Degeneration. THE LIPOFUSCIN COMPONENT N-RETINYL-N-RETINYLIDENE ETHANOLAMINE DETACHES PROAPOPTOTIC PROTEINS FROM MITOCHONDRIA AND INDUCES APOPTOSIS IN MAMMALIAN RETINAL PIGMENT EPITHELIAL CELLS J. Biol. Chem., December 8, 2000; 275(50): 39625 - 39630. [Abstract] [Full Text] [PDF]