Detergent-solubilized bovine cytochrome c oxidase: Dimerization depends on the amphiphilic environment

A. Musatov, J. Ortega-Lopez, N. C. Robinson

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Abstract

The extent to which bovine cytochrome c oxidase (COX) dimerizes in nondenaturing detergent environments was assessed by sedimentation velocity and equilibrium. In contrast to generally accepted opinion, the COX dimer is difficult to maintain and is the major oligomeric form only when COX is solubilized with a low concentration of dodecylmaltoside, i.e., ~1 mg/mg protein. The dimer form is intrinsically unstable and dissociates into monomers with increased detergent concentration, i.e., > 5 mg/mg protein. The structure of the solubilizing detergent, however, greatly alters detergent effectiveness by inducing either monomerization or aggregation. Triton X-100 is most effective at solubilizing COX, but it destabilizes COX dimers, even at low concentration. Undecylmaltoside, decylmaltoside, and octaethyleneglycolmonododecyl ether (C12E8) are less effective at solubilizing COX. Each prevents COX aggregation at high detergent concentration, but also destabilizes the COX dimer. Other detergents, e.g., Tween 20, sodium cholate, sodium deoxycholate, CHAPS, or CHAPSO, are completely ineffective COX solubilizers and do not prevent aggregation even at 10-40 mg/mL. The transition from dimers to monomers depends on many factors other than detergent structure and concentration, e.g., protein concentration, phospholipid content and pH. We conclude that the intrinsic dimeric structure of COX can be maintained only after solubilization with low concentrations of dodecylmaltoside at near neutral pH, and even then precautions must be taken to prevent its dissociation into monomers.

Original languageEnglish (US)
Pages (from-to)12996-13004
Number of pages9
JournalBiochemistry
Volume39
Issue number42
DOIs
StatePublished - Oct 24 2000

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Dimerization
Electron Transport Complex IV
Detergents
Oxidoreductases
Dimers
Agglomeration
Monomers
Sodium Cholate
Proteins
Deoxycholic Acid
Polysorbates
Octoxynol
Sedimentation
Ether
Phospholipids

ASJC Scopus subject areas

  • Biochemistry

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Detergent-solubilized bovine cytochrome c oxidase : Dimerization depends on the amphiphilic environment. / Musatov, A.; Ortega-Lopez, J.; Robinson, N. C.

In: Biochemistry, Vol. 39, No. 42, 24.10.2000, p. 12996-13004.

Research output: Contribution to journalArticle

Musatov, A. ; Ortega-Lopez, J. ; Robinson, N. C. / Detergent-solubilized bovine cytochrome c oxidase : Dimerization depends on the amphiphilic environment. In: Biochemistry. 2000 ; Vol. 39, No. 42. pp. 12996-13004.
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