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Conformational equilibria and dynamics of cytochrome c induced by binding of sodium dodecyl sulfate monomers and micelles
Zitatschlüssel ISI:000186684100002
Autor Oellerich, S and Wackerbarth, H and Hildebrandt, P
Seiten 599-613
Jahr 2003
ISSN 0175-7571
DOI 10.1007/s00249-003-0306-y
Adresse 175 FIFTH AVE, NEW YORK, NY 10010 USA
Journal European biophysics journal with biophysics letters
Jahrgang 32
Nummer 7
Monat NOV
Verlag SPRINGER-VERLAG
Zusammenfassung Circular dichroism, nuclear magnetic resonance, electron paramagnetic resonance, UV-vis absorption, and resonance Raman (RR) spectroscopic techniques were employed to study protein and heme structural changes of cytochrome e (Cyt-c) induced by sodium dodecyl sulfate (SDS) monomers and micelles via hydrophobic and electrostatic interactions, respectively. Both modes of interactions cause the transition to the conformational state B2, which is implicated to be involved in the physiological processes of Cyt-c. At submicellar concentrations of SDS, specific binding of only ca. three SDS monomers, which is likely to occur at the hydrophobic peptide segment 81-85, is sufficient for a complete conversion to a B2 state in which Met80 is replaced by His33 (His26). These heme pocket structural changes are not linked to secondary structure changes of the protein brought about by nonspecific binding of SDS monomers in different regions of the protein. Upon binding of micelles, B2 high-spin species can also be stabilized by electrostatic interactions. In addition, the micelle interaction domain is located on the front surface of Cyt-c, which includes a ring-like arrangement of lysine residues appropriate for binding one micelle. According to freeze-quench RR and stopped-flow experiments, state B2 is formed on the long millisecond timescale and reveals a complex dependence on the SDS concentration that can be interpreted in terms of competitive binding of monomers and micelles.
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