AVS 49th International Symposium
    Biomaterials Tuesday Sessions
       Session BI-TuP

Paper BI-TuP17
Explorations of the Influence of Electrostatic Interactions on Surface-Peptide Binding by Matrix-Assisted Laser Desorption / Ionization Mass Spectrometry

Tuesday, November 5, 2002, 5:30 pm, Room Exhibit Hall B2

Session: Biointerfaces and Surfaces I
Presenter: J. Zhang, University of Texas at Arlington
Authors: G.R. Kinsel, University of Texas at Arlington
J. Zhang, University of Texas at Arlington
R.B. Timmons, University of Texas at Arlington
M. Li, University of Texas at Arlington
Correspondent: Click to Email
Protein-surface interactions play an important role in a variety of fields. The mechanism of these interactions remains unclear, however, due to the extraordinary complexity of the protein-surface interface and the wide range of chemical and morphological properties that may be present. The use of well characterized surfaces and peptides with well-defined properties can alleviate some of these problems and allow the systematic study of the influence of various surface or protein properties on the protein-surface binding interactions. In the present studies surfaces having well characterized chemical and morphological properties have been created by plasma polymerization of allyl amine or vinyl acetic acid leading to surfaces with high contents of amine or carboxylic acid functional groups respectively. Bradykinin, angiotensin I, and buccalin are three small peptides with similar molecular weights but various primary sequences leading to systematic changes in the peptide pI from 12.0 to 6.9 to 3.8 respectively. It is shown that these peptides have increasing binding affinity for plasma polymerized vinyl acetic acid modified PET surfaces, but decreasing binding affinity for plasma polymerized allyl amine modified PET surfaces. These trends may be attributed to electrostatic interactions between the peptides and the chemical groups on the plasma modified surfaces. This interpretation of the observed effects can be further explored by altering the pH of the solution in which the binding interactions take place. For example, it is found that as the acidity of the solution is increased binding of the acidic peptide to the basic surface is reduced, consistent with the peptide being neutralized in low pH solutions. Additional studies that explore the effect of solution pH on peptide surface binding interactions have been performed and are interpreted in terms of the changing electrostatic properties of the peptide and surface.