title: Approximate calculation and experimental derivation of native isoelectric points of membrane protein complexes of Arabidopsis chloroplasts and mitochondria.
abstract: Electric charges are important intrinsic properties of proteins. They directly affect functionality and also mediate interactions with other molecules such as cofactors, substrates and regulators of enzymatic activity, with lipids as well as other proteins. As such, analysis of the electric properties of proteins gives rise to improved understanding of the mechanism by which proteins fulfil their specific functions. This is not only true for singular proteins but also applies for defined assemblies of proteins, protein complexes and supercomplexes. Charges in proteins often are a consequence of the presence of basic and acidic amino acid residues within polypeptide chains. In liquid phase, charge distributions of proteins change in response to the pH of their environment. The interdependence of protein charge and the surrounding pH is best described by the isoelectric point, which is notoriously difficult to obtain for native protein complexes. Here, experimentally derived native isoelectric points (npIs) for a range mitochondrial and plastid protein complexes are provided. In addition, for four complexes, npIs were calculated by a novel approach which yields results largely matching the experimental npIs.
authors.affiliation: Institute for Plant Genetics, Leibniz University of Hannover, Germany.
authors.forename: Christof
authors.initials: C
authors.lastname: Behrens
authors.forename: Kristina
authors.initials: K
authors.lastname: Hartmann
authors.forename: Stephanie
authors.initials: S
authors.lastname: Sunderhaus
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Braun
authors.forename: Holger
authors.initials: H
authors.lastname: Eubel
mesh_terms: D000818:Animals; D017360:Arabidopsis / Q000378:metabolism*; D001703:Biophysics / Q000379:methods; D002417:Cattle; D002736:Chloroplasts / Q000378:metabolism*; D005656:Fungal Proteins / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007525:Isoelectric Focusing / Q000379:methods; D007526:Isoelectric Point; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000378:metabolism; D013058:Mass Spectrometry / Q000379:methods; D008565:Membrane Proteins / Q000737:chemistry*; D008928:Mitochondria / Q000378:metabolism*; D008958:Models, Molecular; D018087:Plastids / Q000378:metabolism; D014867:Water / Q000737:chemistry
chemical_list: D005656:Fungal Proteins; D045342:Light-Harvesting Protein Complexes; D008565:Membrane Proteins; D014867:Water