Enhanced molecular chaperone activity of the small heat-shock protein αB-crystallin following covalent immobilization onto a solid-phase support

The well‐characterized small heat‐shock protein, αB‐crystallin, acts as a molecular chaperone by interacting with unfolding proteins to prevent their aggregation and precipitation. Structural perturbation (e.g., partial unfolding) enhances the in vitro chaperone activity of αB‐crystallin. Proteins often undergo structural perturbations at the surface of a synthetic material, which may alter their biological activity. This study investigated the activity of αB‐crystallin when covalently bound to a support surface; αB‐crystallin was immobilized onto a range of solid material surfaces, and its characteristics and chaperone activity were assessed. Immobilization was achieved via a plasma‐deposited thin polymeric interlayer containing aldehyde surface groups and reductive amination, leading to the covalent binding of αB‐crystallin lysine residues to the surface aldehyde groups via Schiff‐base linkages. Immobilized αB‐crystallin was characterized by X‐ray photoelectron spectroscopy, atomic force microscopy, and quartz crystal microgravimetry, which showed that ∼300 ng cm−2 (dry mass) of oligomeric αB‐crystallin was bound to the surface. Immobilized αB‐crystallin exhibited a significant enhancement (up to 5000‐fold, when compared with the equivalent activity of αB‐crystallin in solution) of its chaperone activity against various proteins undergoing both amorphous and amyloid fibril forms of aggregation. The enhanced molecular chaperone activity of immobilized αB‐crystallin has potential applications in preventing protein misfolding, including against amyloid disease processes, such as dialysis‐related amyloidosis, and for biodiagnostic detection of misfolded proteins. © 2011 Wiley Periodicals, Inc. Biopolymers 95: 376–389, 2011