Abstract

VERA-BRAVO, Ricardo; J SCOTTER, Andrew; DAVIES, Peter L  and  BLANCO, Luis H. De novo DESIGN AND SYNTHESIS OF AN ICE-BINDING, DENDRIMERIC, POLYPEPTIDE BASED ON INSECT ANTIFREEZE PROTEINS. Rev.Colomb.Quim. [online]. 2012, vol.41, n.1, pp.133-157. ISSN 0120-2804.

A new strategy is presented for the design and synthesis of peptides that exhibit ice-binding and antifreeze activity. A pennant-type dendrimer polypeptide scaffoíd combining an a-helical backbone with four short (β-strand branches was synthesized in solid phase using Fmoc chemistry in a divergent approach. The 51-residue dendrimer was characterized by reverse phase high performance liquid chromatography, mass spectrometry and circular dichroism. Each (β-strand branch contained three overlapping TXT amino acid repeats, an ice-binding motif found in the ice-binding face of the spruce budworm (Choristoneura fumiferana) and beetle (Tenebrio molitor) antifreeze proteins. Ice crystals in the presence of the polypeptide monomer displayed fiat, hexagonal plate morphology, similar to that produced by weakly active antifreeze proteins. An oxidized dimeric form of the dendrimer polypeptide also produced fiat hexagonal ice crystals and was capable of inhibiting ice crystal growth upon temperature reduction, a phenomenon termed thermal hysteresis, a defining property of antifreeze proteins. Linkage of the pennant-type dendrimer to a tri-functional cascade-type polypeptide produced a trimeric macromolecule that gave flat hexagonal ice crystals with higher thermal hysteresis activity than the dimer or monomer and an ice crystal burst pattern similar to that produced by samples containing insect antifreeze proteins. This macromolecule was also capable of inhibiting ice recrystallization.

Keywords : Antifreeze protein; den-drimer; synthetic polypeptide; thermal hysteresis; ice recrystallization inhibition.

        · abstract in Spanish | Portuguese     · text in English     · English ( pdf )