Synthesis of peptide gels for the investigation of oligopeptide-oligonucleotide interactions

Free radical induced polymerization of synthetic peptides into polymeric immunogens

Free radical induced polymerization of vinyl monomers such as the acryloyl peptides described here is a facile and rapid reaction used routinely, for example, in the polymerization of acrylamide and bisacrylamide for the assembly of polyacrylamide gels. The technology allows the incorporation of many of the same or different peptide determinants into a single polymer chain. In this study large polymers containing multiple copies of peptides representing T- and B-cell determinants of influenza haemagglutinin were constructed. The determinants retained antigenicity after the polymerization procedure and the polymers were highly immunogenic; the levels of antibody obtained after a single dose of polymeric immunogen were at least as great as those achieved only after repeated doses of the equivalent monomeric peptide. The technology has a wide range of potential applications, not the least significant of which is the construction of designer immunogens for third generation vaccine candidates.

Modulation of 5'-nucleotidase activity in plasma membranes and intact cells by the extracellular matrix proteins laminin and fibronectin

Modulation of 5'-nucleotidase activity by the extracellular matrix proteins fibronectin, laminin and their fragments has been studied in plasma membrane preparations as well as in intact BCS-TC2 and Rugli cells. The ectoenzyme on plasma membranes is activated by laminin; fibronectin inhibits the AMPase activity on BCS-TC2 plasma membranes but no inhibitory effect is found in plasma membrane preparations from Rugli cells. These effects are dependent on the preincubation time and protein concentration. When the effect of the extracellular matrix proteins is studied on intact cells, both BCS-TC2 and Rugli cells show similar behaviour. A decrease in the enzyme activity is observed in the presence of fibronectin. The AMPase inhibitory activity is located on its 40 kDa fragment. No inhibitory activity is found in other fibronectin fragments, including the 140 kDa fragment which contains the RGDS cell-adhesion sequence. Laminin and its E1-4 and E8 fragments are able to activate the ecto-5'-nucleotidase activity of both BCS-TC2 and Rugli cells. The effect of the E1-4 fragment on intact cells is greater than that observed for the E8 fragment and uncleaved laminin. Our results suggest a bifunctional role for 5'-nucleotidase as ectoenzyme and cell receptor for extracellular matrix proteins.