title: Adsorption mechanism of myelin basic protein on model substrates and its bridging interaction between the two surfaces.
abstract: Myelin basic protein (MBP) is an intrinsically disordered (unstructured) protein known to play an important role in the stability of myelin's multilamellar membrane structure in the central nervous system. The adsorption of MBP and its capacity to interact with and bridge solid substrates has been studied using a surface forces apparatus (SFA) and a quartz crystal microbalance with dissipation (QCM-D). Adsorption experiments show that MBP molecules adsorb to the surfaces in a swollen state before undergoing a conformational change into a more compact structure with a thickness of ∼3 nm. Moreover, this compact structure is able to interact with nearby mica surfaces to form adhesive bridges. The measured adhesion force (energy) between two bridged surfaces is 1.0 ± 0.1 mN/m, (Ead = 0.21 ± 0.02 mJ/m(2)), which is slightly smaller than our previously reported adhesion force of 1.7 mN/m (Ead = 0.36 mJ/m(2)) for MBP adsorbed on two supported lipid bilayers (Lee et al., Proc. Natl. Acad. Sci. U.S.A. 2014, 111, E768-E775). The saturated surface concentration of compact MBP on a single SiO2 surface reaches a stable value of 310 ± 10 ng/cm(2) regardless of the bulk MBP concentration. A kinetic three-step adsorption model was developed that accurately fits the adsorption data. The developed model is a general model, not limited to intrinsically disordered proteins, that can be extended to the adsorption of various chemical compounds that undergo chemical reactions and/or conformational changes upon adsorbing to surfaces. Taken together with our previously published data (Lee et al., Proc. Natl. Acad. Sci. U.S.A. 2014, 111, E768-E775), the present results confirm that conformational changes of MBP upon adsorption are a key for strong adhesion, and that such conformational changes are strongly dependent on the nature of the surfaces.
authors.affiliation: †Department of Chemical Engineering, University of California at Santa Barbara, Santa Barbara, California 93106, United States.
authors.forename: Dong Woog
authors.initials: DW
authors.lastname: Lee
authors.affiliation: ‡Canada Research Chair in Bio-inspired Materials and Interfaces, Faculty of Pharmacy, Université de Montréal C.P. 6128, succursale Centre Ville, Montréal, Québec H3C 3J7, Canada.
authors.forename: Xavier
authors.initials: X
authors.lastname: Banquy
authors.affiliation: †Department of Chemical Engineering, University of California at Santa Barbara, Santa Barbara, California 93106, United States.
authors.forename: Kai
authors.initials: K
authors.lastname: Kristiansen
authors.affiliation: §Department of Polymer Engineering, University of Akron, Akron, Ohio United States.
authors.forename: Younjin
authors.initials: Y
authors.lastname: Min
authors.affiliation: ∥Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada.
authors.forename: Arun
authors.initials: A
authors.lastname: Ramachandran
authors.affiliation: ⊥Department of Molecular Structure and Function, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada.|#Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario M5G 1L5, Canada.
authors.forename: Joan M
authors.initials: JM
authors.lastname: Boggs
authors.affiliation: †Department of Chemical Engineering, University of California at Santa Barbara, Santa Barbara, California 93106, United States.|∇Materials Department, University of California, Santa Barbara, California 93106, United States.
authors.forename: Jacob N
authors.initials: JN
authors.lastname: Israelachvili
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates / Q000737:chemistry; D000818:Animals; D002417:Cattle; D007700:Kinetics; D008051:Lipid Bilayers / Q000737:chemistry; D008958:Models, Molecular; D004676:Myelin Basic Protein / Q000737:chemistry*; D011487:Protein Conformation; D013499:Surface Properties
chemical_list: D000538:Aluminum Silicates; D008051:Lipid Bilayers; D004676:Myelin Basic Protein; C011934:mica