Surface-dependent conformations of human plasma fibronectin adsorbed to silica, mica, and hydrophobic surfaces, studied with use of Atomic Force Microscopy.
Human plasma fibronectin (Fn) is a large flexible protein stabilized by intermolecular ionic interactions forming a compact structure. On altering solution conditions, the structure can revert to a more expanded state, thereby exposing previously hidden domains (e.g., cell-binding sites). Electron microscopy images of Fn air-sprayed onto mica surfaces show elongated protein structures, indicating a surface-induced structural change. This makes it interesting to investigate the influence of surface properties on the structure of adsorbed Fn. We have used intermittent-contact Atomic Force Microscopy to investigate the structure of Fn adsorbed onto mica, silica, and methylated silica surfaces. We observed that on silica surfaces, which is hydrophilic, most (70%) of the molecules had an elongated structure with partial intramolecular chain interactions, compare to molecules adsorbed on hydrophobic, methylated surfaces, where a compact structure predominated (70%). On mica surfaces, both compact and elongated protein structures were observed, with a slight preference for the elongated form (53%). Results show that surface physical properties influence the molecular structure of fibronectin on adsorption, which could provide useful information in understanding surface-induced in vivo responses.
Bergkvist
Magnus
M
Department of Biology and Chemical Engineering, Mälardalen University, Box 325, S-63105 Eskilstuna, Sweden. magnus.bergkvist@mdh.se
Carlsson
Jan
J
Oscarsson
Sven
S
D000042:Absorption; D000538:Aluminum Silicates; D005353:Fibronectins / Q000737:chemistry* / Q000648:ultrastructure; D018625:Microscopy, Atomic Force; D008958:Models, Molecular; D011487:Protein Conformation; D012822:Silicon Dioxide; D013499:Surface Properties
D000538:Aluminum Silicates; D005353:Fibronectins; D012822:Silicon Dioxide; C011934:mica