Coulombic and noncoulombic effect of polyanions on cytochrome c structure

The properties of the complexes of ferricytochrome c with two different polyanions—poly(vinylsulfate) and poly(4‐styrene‐sulfonate)—with a comparable charge density but with the different size of the uncharged part of their molecules have been studied by means of optical spectroscopy, differential s...

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Bibliographic Details
Published in:Biopolymers 1998-09, Vol.46 (3), p.145-154
Main Authors: Sedlák, Erik, Antalík, Marián
Format: Article
Language:English
Subjects:
Animals
Binding Sites
Biopolymers - chemistry
Biopolymers - metabolism
Calorimetry, Differential Scanning
Chromatography, Gel
Circular Dichroism
conformational change
coulombic interaction
cytochrome c
Cytochrome c Group - chemistry
Cytochrome c Group - metabolism
Horses
Hydrogen-Ion Concentration
hydrophobic interaction
In Vitro Techniques
Macromolecular Substances
Membrane Lipids - chemistry
Membrane Proteins - chemistry
microcalorimetry
polyanion binding
Polymers - chemistry
Polymers - metabolism
Polystyrenes - chemistry
Polystyrenes - metabolism
Polyvinyls - chemistry
Polyvinyls - metabolism
Protein Conformation
Spectrophotometry
Thermodynamics
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Summary:The properties of the complexes of ferricytochrome c with two different polyanions—poly(vinylsulfate) and poly(4‐styrene‐sulfonate)—with a comparable charge density but with the different size of the uncharged part of their molecules have been studied by means of optical spectroscopy, differential scanning calorimetry, and gel chromatography. Ferriccytochrome c formed a complex with the former one through coulombic interactions and remained in a native‐like state. The addition of the second polyanion to a solution of ferric cytochrome c at a low ionic strength, pH 7.0, resulted in profound conformational change in the hydrophobic core of protein (opening of the heme crevice with a perturbation of the methionine 80‐heme iron bond and the hydrophobic core of the protein). These may be understood as an involvement of noncoulombic (hydrophobic, H‐bonding) interactions of the uncharged part of the polyanion molecule. Conformational changes and the observed shift in acidic transition from low spin to high spin state of ferric cytochrome c detected in the presence of the polyanions may have biological implication in understanding the origin of conformational changes in proteins induced in the course of their interaction with membrane lipids and membrane proteins. © 1998 John Wiley & Sons, Inc. Biopoly 46: 145–154, 1998
ISSN:0006-3525
1097-0282
DOI:10.1002/(SICI)1097-0282(199809)46:3<145::AID-BIP2>3.0.CO;2-L