title: AFM visualization at a single-molecule level of denaturated states of proteins on graphite.
abstract: Different graphitic materials are either already used or believed to be advantageous in biomedical and biotechnological applications, e.g., as biomaterials or substrates for sensors. Most of these applications or associated important issues, such as biocompatibility, address the problem of adsorption of protein molecules and, in particular the conformational state of the adsorbed protein molecule on graphite. High-resolution AFM demonstrates highly oriented pyrolytic graphite (HOPG) induced denaturation of four proteins of blood plasma, such as ferritin, fibrinogen, human serum albumin (HSA) and immunoglobulin G (IgG), at a single molecule level. Protein denaturation is accompanied by the decrease of the heights of protein globules and spreading of the denatured protein fraction on the surface. In contrast, the modification of HOPG with the amphiphilic oligoglycine-hydrocarbon derivative monolayer preserves the native-like conformation and provides even more mild conditions for the protein adsorption than typically used mica. Protein unfolding on HOPG may have universal character for "soft" globular proteins.
authors.affiliation: Federal Research and Clinical Center of Physical-Chemical Medicine, Malaya Pirogovskaya, 1a, Moscow 119435 Russian Federation.
authors.forename: Nikolay A
authors.initials: NA
authors.lastname: Barinov
authors.affiliation: Federal Research and Clinical Center of Physical-Chemical Medicine, Malaya Pirogovskaya, 1a, Moscow 119435 Russian Federation.
authors.forename: Valery V
authors.initials: VV
authors.lastname: Prokhorov
authors.affiliation: Federal Research and Clinical Center of Physical-Chemical Medicine, Malaya Pirogovskaya, 1a, Moscow 119435 Russian Federation; Lomonosov Moscow State University, Leninskie gory, 1-2, Moscow 119991, Russian Federation. Electronic address: dubrovin@polly.phys.msu.ru.
authors.forename: Evgeniy V
authors.initials: EV
authors.lastname: Dubrovin
authors.affiliation: Federal Research and Clinical Center of Physical-Chemical Medicine, Malaya Pirogovskaya, 1a, Moscow 119435 Russian Federation; Moscow Institute of Physics and Technology (State University), Institutskiy per. 9, Dolgoprudny, 141700, Moscow region, Russian Federation. Electronic address: klinov.dmitry@mail.ru.
authors.forename: Dmitry V
authors.initials: DV
authors.lastname: Klinov
mesh_terms: D000327:Adsorption; D006108:Graphite / Q000737:chemistry*; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry*; D018625:Microscopy, Atomic Force / Q000379:methods*; D008968:Molecular Conformation; D036103:Nanotechnology; D011489:Protein Denaturation; D012709:Serum Albumin / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D007074:Immunoglobulin G; D012709:Serum Albumin; D006108:Graphite
keywords: Atomic force microscopy; Graphite; Protein adsorption; Protein denaturation