ADSORPTION OF HEME-CONTAINING PEPTIDES ON SILICON SURFACES

To elucidate the role of minor alteration of amino acid composition of protein in interfacial behavior, the adsorption of three heme peptides on hydrophilic and hydrophobic silicon surfaces was studied. It was found that all three peptides did not adsorb on the hydrophilic silicon surfaces and irreversibly adsorbed on the hydrophobic silica prepared by pretreatment with dimethyldichlorosilane. Rate constants of adsorption at pH = 7.2 for all the heme peptides were the same, indicating that at the initial stage of adsorption heme peptides interacted with the hydrophobic surface through identical segments. On the basis of plateau values obtained, calculation of surface areas occupied per heme peptide molecule showed that the higher the heme peptide molecular mass, the smaller is its occupied area on the hydrophobic silicon surface at pH = 7.2. This "illogical" observation was explored by electrostatic interaction of adsorbed heme peptide molecules, on the basis of their a bell-shaped pH-dependent adsorption and on the pKa values of amino acid residues in heme peptides. © 1992.