title: KfrA plasmid protein monolayers on latex particles-electrokinetic measurements.
abstract: Monolayers of KfrA, a protein assisting in bacteria plasmid segregation, on polystyrene latex particles were produced in controlled self-assembling under diffusion-controlled conditions. The coverage of the protein was quantitatively determined as a function of ionic strength (up to 0.15 M, NaCl) via micro-electrophoretic measurements and concentration depletion with the aid of AFM imaging. The maximum monolayer coverage of KfrA  monotonically increased with ionic strength attaining 2.0 mg m(-2) for 0.15 M, NaCl that corresponds to the dimensionless coverage of 0.48. This is in accordance with theoretical calculations derived from the random sequential adsorption modeling assuming a tetrameric aggregation state. A high stability of the monolayers in pH cycling experiments was confirmed, which proves the irreversibility of protein adsorption on latex. The acid base properties and the electrokinetic charge of monolayers were also determined via the electrophoretic mobility measurements carried out for various ionic strength. In this way the isoelectric point of the protein of 4.8 was determined, which is prohibitive via bulk measurements. It was concluded that the procedure used in our work is reliable and efficient for characterizing physicochemical properties if minor amounts of a protein are available.
authors: Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, Niezapominajek 8, 30-239 Cracow, Poland.
authors: Marta
authors: M
authors: Kujda
authors: Zbigniew
authors: Z
authors: Adamczyk
authors: Grazyna
authors: G
authors: Jagura-Burdzy
authors: Małgorzata
authors: M
authors: Adamczyk
mesh_terms: D000327:Adsorption; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics; D004563:Electrochemistry; D004591:Electrophoresis, Polyacrylamide Gel; D007526:Isoelectric Point; D007840:Latex; D008027:Light; D009994:Osmolar Concentration; D010957:Plasmids / Q000235:genetics; D055503:Protein Multimerization; D055550:Protein Stability; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D012542:Scattering, Radiation; D013499:Surface Properties
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D007840:Latex; D011994:Recombinant Proteins
keywords: Isoelectric point of KfrA; KfrA plasmid protein adsorption; KfrA plasmid protein properties; Latex covered by KfrA plasmid protein; Monolayers of KfrA protein on latex; Plasmid protein adsorption on latex