title: Advantages and limitations of clear-native PAGE.
abstract: Clear-native PAGE (CN-PAGE) separates acidic water-soluble and membrane proteins (pI < 7) in an acrylamide gradient gel, and usually has lower resolution than blue-native PAGE (BN-PAGE). The migration distance depends on the protein intrinsic charge, and on the pore size of the gradient gel. This complicates estimation of native masses and oligomerization states when compared to BN-PAGE, which uses negatively charged protein-bound Coomassie-dye to impose a charge shift on the proteins. Therefore, BN-PAGE rather than CN-PAGE is commonly used for standard analyses. However, CN-PAGE offers advantages whenever Coomassie-dye interferes with techniques required to further analyze the native complexes, e.g., determination of catalytic activities, as shown here for mitochondrial ATP synthase, or efficient microscale separation of membrane protein complexes for fluorescence resonance energy transfer (FRET) analyses. CN-PAGE is milder than BN-PAGE. Especially the combination of digitonin and CN-PAGE can retain labile supramolecular assemblies of membrane protein complexes that are dissociated under the conditions of BN-PAGE. Enzymatically active oligomeric states of mitochondrial ATP synthase previously not detected using BN-PAGE were identified by CN-PAGE.
authors.affiliation: Zentrum der Biologischen Chemie, Fachbereich Medizin, Universität Frankfurt, Germany.
authors.forename: Ilka
authors.initials: I
authors.lastname: Wittig
authors.forename: Hermann
authors.initials: H
authors.lastname: Schägger
mesh_terms: D000251:Adenosine Triphosphatases / Q000302:isolation & purification*; D015119:Aminocaproic Acid / Q000737:chemistry; D002384:Catalysis; D004072:Digitonin / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods*; D007093:Imidazoles / Q000737:chemistry; D007202:Indicators and Reagents; D008565:Membrane Proteins / Q000302:isolation & purification*; D025261:Mitochondrial Proton-Translocating ATPases / Q000302:isolation & purification*; D010085:Oxidative Phosphorylation; D011506:Proteins / Q000302:isolation & purification*; D015203:Reproducibility of Results
chemical_list: D007093:Imidazoles; D007202:Indicators and Reagents; D008565:Membrane Proteins; D011506:Proteins; C029899:imidazole; D000251:Adenosine Triphosphatases; D025261:Mitochondrial Proton-Translocating ATPases; D004072:Digitonin; D015119:Aminocaproic Acid