Effects on protein conformation of binding to
nanoparticles
Proteins are chains of amino acids, where the exact sequence of the
amino acids determines the protein’s shape, structure, and function.
The principle units of protein secondary structure are α-helices and
β-sheets, and the three-dimensional arrangement of these is the
tertiary structure (α-helix, shown in red, and β-strand, blue, structures
are illustrated in Fig. 1). The native conformation of a protein is tightly
controlled by the shape complementarity of the hydrophobic residues
that allow close packing of the cores28. Proteins are nevertheless
marginally stable because the beneficial interactions that govern the
native structure are counterbalanced by a large entropy loss associated
with going from a large ensemble of states to a more restricted set
of conformations, as well as by the repulsive electrostatic interactions
present in the native state29. Thus, interaction with a surface can easily
disrupt the native conformation and, therefore, the protein function.
This has implications for the biological impact of nanoparticles.