Semiconductor-binding synthetic peptides

After these general considerations on the adsorption behavior of heteropolymers on simple-cubic lattices, we will investigate sequence-specific adhesion properties of semiconductor-binding synthetic peptides in the following. 

Let us now discuss a real-world example of some synthetic peptides that exhibit distinct binding properties to semiconductor substrates. For this purpose, we are going to discuss the solution and adsorption behavior of synthetic 12-residue peptides, whose adhesion properties to surfaces of GaAs and Si crystals were the subject of extensive experiments [274-276,340]. 

GaAs( 100) is chosen as a reference substrate, because the peptides listed in Table 14.1 bind comparatively well to this substrate. The cPAC values for the peptides discussed here in more detail are also given in Table 14.1. 

The main question is how these differences in binding behavior occur. From the experiments, it is known that the bound peptides form clusters on the substrate [276], but it is unlikely that the peptides aggregate before binding to the surface, because the hydropho-bicity of the peptides studied is low and the peptide concentration was extremely low, in the nanomolar range. Measurements of circular dichroism (CD) spectra suggest that all four experimentally studied small peptides are, as expected, largely unstmctured in solution [276]. 

It has been argued that the adhesion propensity of peptides to various surfaces can be partially explained in terms of individual adhesion properties of their constituent amino acids [277,342]. However, the amino acid composition alone caimot explain the PAC values obtained experimentally for the peptides studied here. In fact, some of these peptides share exactly the same amino acid composition, but still have quite different adhesion properties (SI and S3). In order to explain the adhesion properties, it might thus be necessary to take structural characteristics into accoimt, although, as already indicated, CD measurements at room temperature do not reveal any clear stmctural differences between these peptides. 

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