Adsorption kinetics of an engineered gold binding Peptide by surface plasmon resonance spectroscopy and a quartz crystal microbalance.
ABSTRACT The adsorption kinetics of an engineered gold binding peptide on gold surface was studied by using both quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) spectroscopy systems. The gold binding peptide was originally selected as a 14-amino acid sequence by cell surface display and then engineered to have a 3-repeat form (3R-GBP1) with improved binding characteristics. Both sets of adsorption data for 3R-GBP1 were fit to Langmuir models to extract kinetics and thermodynamics parameters. In SPR, the adsorption onto the surface shows a biexponential behavior and this is explained as the effect of bimodal surface topology of the polycrystalline gold substrate on 3R-GBP1 binding. Depending on the concentration of the peptide, a preferential adsorption on the surface takes place with different energy levels. The kinetic parameters (e.g., K(eq) approximately 10(7) M(-1)) and the binding energy (approximately -8.0 kcal/mol) are comparable to synthetic-based self-assembled monolayers. The results demonstrate the potential utilization of genetically engineered inorganic surface-specific peptides as molecular substrates due to their binding specificity, stability, and functionality in an aqueous-based environment.
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ABSTRACT: We investigate the interaction between D-Ala-D-Ala peptide and a stainless steel (SS) surface by AFM force spectroscopy with view to understand the role and nature of interfacial processes at the single molecule level. For this purpose, force-distance curves were recorded between the D-Ala-D-Ala modified tip and the SS surface in NaHCO(3)-enriched medium. The SS surface was prepared in a way that allows iron oxide species, presumably FeOOH, to be formed and remains stable during AFM measurements. Dynamic force measurements show that the unbinding force linearly increases with the logarithm of the loading rate, as generally observed for receptor–ligand complexes. Our results reveal also the existence of two regimes, suggesting the presence of multiple energy barriers in the energy landscape. From these dynamic force spectroscopy measurements, the kinetic off-rate constant is determined. An average unbinding force in the range of 50-300 pN is obtained, depending on the loading rate. Accordingly, in a medium in which the electrostatic interactions are not dominating, the binding mechanism of the peptide and SS surface cannot be attributed to covalent bonds and may be due to a combination of van der Waals and hydrogen bonds. Our findings open up new way to probe peptide-inorganic surface interactions and to understand the mechanism of peptide specific binding which is of particular interest in the design of hybrid materials.ChemPhysChem 05/2011; 12(7):1310-6. · 3.35 Impact Factor
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ABSTRACT: Thesis (Ph. D.)--Massachusetts Institute of Technology, Biological Engineering Division, 2007. MIT Science Library copy: printed in leaves. Also issued printed in leaves. Includes bibliographical references (p. 127-141). Utilizing molecular recognition and self-assembly, material-specific biomolecules have shown great promise for engineering and ordering materials at the nanoscale. These molecules, inspired from natural biomineralization systems, are now commonly selected against non-natural inorganic materials through biopanning random combinatorial peptide libraries. Unfortunately, the challenge of studying the biological inorganic interface has slowed the understanding of interactions principles, and hence limited the number of downstream applications. This work focuses on the facile study of the peptide-inorganic interface using Yeast Surface Display. The general approach is to use combinatorial selection to suggest interaction principles followed by rational design to refine understanding. In this pursuit, two material groups-II-VI semiconductors and synthetic sapphire (metal oxides)-are chosen as inorganic targets due to their technological relevance and ease of study. First, yeast surface display (YSD) was established as a broadly applicable method for studying peptide-material interactions by screening a human scFv YSD library against cadmium sulfide (CdS), a II-VI semiconductor. The presence of multiple histidine residues was found to be necessary for mediating cell binding to CdS. As a follow-up, a systematic screen with yeast displayed rationally designed peptides was performed on a panel of II-VI semiconductors and gold. Cell binding results indicated that peptide interaction was mediated by a limited number of amino acids that were influenced by locally situated residues. Interpretation of the results facilitated design of new peptides with desired material specificities. Next, the nature of peptide/metal oxide binding interface was interrogated using sapphire crystalline faces as model surfaces. (cont.) Biopanning a random peptide YSD library and subsequent characterization of the identified binding partners revealed the importance of multiple basic amino acids in the binding event. Study of rationally designed basic peptides revealed a preference for those amino acids to be spaced in such a manner that maximized simultaneous interaction with the surface. Fusing peptides to maltose binding protein (MBP) allowed for quantitative affinity measurement with the best peptides having low nanomolar equilibrium dissociation constants. Finally, peptides were demonstrated as facile affinity tags for protein immobilization in micro-patterning and biosensor assays. by Eric Mark Krauland. Ph.D.
- ChemBioChem 10/2010; 11(15):2108-12. · 3.74 Impact Factor