Open AccessStructure and dynamics of lipid‐associated states of apocytochrome c
Author(s) -
Bryson Elzbieta A,
Rankin Saffron E.,
Goormaghtigh Erik,
Ruysschaert JeanMarie,
Watts Anthony,
Pinheiro Teresa J. T.
Publication year - 2000
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.2000.01138.x
Subject(s) - membrane , chemistry , folding (dsp implementation) , amide , helix (gastropod) , crystallography , lipid bilayer , kinetics , biophysics , biochemistry , biology , ecology , physics , quantum mechanics , snail , electrical engineering , engineering
Apocytochrome c (apocyt c ), which in aqueous solution is largely unstructured, acquires an α‐helical conformation upon association with lipid membranes. The extent of α‐helix induced in apocyt c is lipid‐dependent and this folding process is driven by both electrostatic and hydrophobic lipid–protein interactions. The structural and dynamic properties of apocyt c in lipid membranes were investigated by attenuated total reflection Fourier transform infrared spectroscopy combined with amide H–D exchange kinetics. Apocyt c acquires a higher content of α‐helical structure with negatively charged membranes than with zwitterionic ones. For all membranes studied here, the helices of these partially folded states of apocyt c have a preferential orientation perpendicular to the plane of the lipid membrane. The H–D exchange revealed that a small fraction of amide protons of apocyt c , possibly associated with a stable folded domain protected by the lipid, remained protected from exchange over 20 min. However, a large fraction of amide protons exchanged in less than 20 min, indicating that the helical states of apocyt c in lipid membranes are very dynamic.