Interaction of cytochrome c with cardiolipin: an infrared spectroscopic study.
The interactions of cytochrome c (cyt c) with cardiolipin, a major anionic phospholipid of mitochondrial membranes, and dioleoylphosphatidylglycerol (DOPG), have been compared by infrared (IR) spectroscopy. The Fourier self-deconvoluted IR spectra of the lipid carbonyl groups indicate that both cyt c3+ and cyt c2+ perturb and/or dehydrate the interfacial region of cardiolipin bilayers. Only a slight perturbation, if any, is observed in the interfacial region of DOPG bilayers. However, the phosphate head region of DOPG is perturbed by cyt c3+, which was not detected in cardiolipin. The results suggest that cytochrome c in both redox states can partially penetrate into cardiolipin but not into DOPG bilayers. The interaction of cyt c with cardiolipin and DOPG is mainly hydrophobic and electrostatic, respectively. The Fourier self-deconvoluted IR spectra in the amide I region reveal that ca. 10% of the cyt c3+ alpha-helix unfolds to random coil upon binding to cardiolipin bilayers. However, only very slight secondary structural changes, if any, were detected when cyt c3+ binds to DOPG bilayers.
Choi
S
S
Department of Chemistry and Biochemistry, Middlebury College, VT 05753, USA.
Swanson
J M
JM
D000577:Amides / Q000032:analysis; D000818:Animals; D002308:Cardiolipins / Q000737:chemistry / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003574:Cytochrome c Group / Q000737:chemistry / Q000378:metabolism*; D006736:Horses; D008051:Lipid Bilayers / Q000378:metabolism; D008055:Lipids / Q000032:analysis; D010710:Phosphates / Q000032:analysis; D010715:Phosphatidylglycerols / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism; D011485:Protein Binding; D017510:Protein Folding; D017433:Protein Structure, Secondary; D013055:Spectrophotometry, Infrared
D000577:Amides; D002308:Cardiolipins; D003574:Cytochrome c Group; D008051:Lipid Bilayers; D008055:Lipids; D010710:Phosphates; D010715:Phosphatidylglycerols; D010743:Phospholipids; C051388:1,2-dioleoyl-sn-glycero-3-phosphoglycerol