Adsorption behavior of linear and cyclic genetically engineered platinum binding peptides

Area of Science:

• Biomaterials Science
• Nanotechnology
• Peptide Engineering

Background:

• Phage and cell-surface display libraries enable selection of peptides that bind inorganic materials.
• Understanding the molecular mechanisms of peptide-inorganic interactions is crucial for their application.
• Current knowledge of binding kinetics and thermodynamics for inorganic-binding peptides is limited.

Purpose of the Study:

• To investigate the impact of structural constraints on the binding characteristics of inorganic-binding peptides.
• To compare the adsorption behavior and conformational properties of a cyclic versus a linear platinum-binding peptide.
• To explore how structural modifications can tune peptide adsorption and binding features for bionanotechnological applications.

Main Methods:

• Synthesized a cyclic (Cys-Cys constrained) and a linear platinum-binding peptide sequence.
• Analyzed peptide adsorption on platinum thin films using surface plasmon resonance (SPR) spectroscopy.
• Determined peptide conformational properties using circular dichroism (CD) spectroscopy and 2,2,2-trifluoroethanol (TFE) titrations.

Main Results:

• The cyclic peptide exhibited significantly higher equilibrium and adsorption rate constants, indicating stronger and faster binding, with 1:1 Langmuir adsorption.
• The linear peptide displayed slower and weaker binding with biexponential Langmuir isotherm behavior.
• Conformational analysis revealed the cyclic peptide adopted a random coil, while the linear peptide adopted a polyproline type II conformation in equilibrium with a random coil.

Conclusions:

• Cys-Cys constraints significantly alter the conformation and binding behavior of platinum-binding peptides.
• Structural constraints can be strategically employed to modulate the adsorption properties of inorganic-binding peptides.
• This study provides a foundation for genetically designing peptides with tailored binding affinities and kinetics for bionanotechnology.