Estructural characterizationof very high density lipoprotein from the spider Polybetes pythagoricus.

LAINO ALDANA; GARCIA FERNANDO; CUNNINGHAM MÓNICA; HERAS HORACIO

Villa Carlos Paz, Córdoba, Argentina

Congreso; XLIV Reunión Anual de la Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular; 2008

Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular

We have prcviously isolated, purified and characterized hemolymphatic VHDL from Polybets pythagoricus. This lipoprotein contains hemocyanin (Hc)as the major apoprotein, as a novelty, it transports most of the circulating lipids. In thc present work, for the tirst time in arachnids, we studied shape and structure P. pythagoricus VHDL using electron microscopy. MALDI-TOF-MS, circular dichroism, proteolysis, N-terminal sequencing, and lipid and cooper specific staining. Results showed that VHDL has spheroidal morphology with estimated size of 11,2 +/- 0.025 nm. As seen by SDS-PAGE, contains one principal band correspondlng to monomers of Hc (70 kDa), and two minor subunits corresponding to non-respiratories proteins of 105 and I20 kDa. These last two proteins are not unit by tlisulfide bonds, they don´t include lipids or copper in your stracture and they would be more exposed to the aqueous medium in native conditions. Using circular dicliroism we observed that contains 20% a-hélice, 29% lámina- B, 22.7% giros and 2% estructra desordenada. By MALDI-TOF MS, 15 polypeptides present in monomer were found to be homologous to subunit 3 of the Cupiennuis salei hemocyanin, and 27 polypeptides from the 105 kDa subunit showed homology to a protein from the Anhopheles gambiae.