This project involves studies on the chemical structure and physicochemical characteristics of certain natural biopolymeric materials and their synthetic analogs with the aim of relating the resulting structural information to their biological mode of action, such as cell growth regulation, cell transformation or differentiation. The modern methods of mass spectrometry, nuclear magnetic resonance and circular dichroism spectroscopies and various chemical methods are being applied. Projects include: (1) development of a fast atom bombardment mass spectrometric method of analyzing disulfide-linked dimeric peptides and of epidermal growth factor (EGF) and transforming growth factor (TGF)-alpha- related cysteine-containing cyclic disulfides. In our approach reductive pyridinoethylation of the peptides yielded derivatives that were better suited for molecular weight and amino acid sequence analysis. In addition a large number of synthetic peptides were analyzed with the molecular weight limit of 2500 for ascertaining the correctness of the synthesis and the oxidation state. (2) Five peptides related to the RGDS segment of the cell attachment factor, fibronectin, were synthesized. This hydrophilic segment in fibronectin interacts with cellular receptors. Circular dichroism studies indicate various molecular conformations for these peptides, the spectrum of the native pentamer indicating a beta turn conformation. The anti-sense peptide, WTVPTA to the native hexamer GRGDSP was also synthesized. Analytical affinity chromatography using the immobilized antisense column demonstrated a dissociation constant of 9x10-4 for the latter two peptides.
