INIBIOLP   05426
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE LA PLATA "PROF. DR. RODOLFO R. BRENNER"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Structure and stability of crustacean lipovitellin: Influence of lipid content and composition
Autor/es:
FERNANDO GARCIA; MONICA CUNNINGHAM; RICARDO POLLERO; HORACIO GARDA
Lugar:
Rosario. Santa Fe, Argentina
Reunión:
Congreso; XXXV reuníon Anual de la Sociedad Argentina de Biofisica.; 2006
Institución organizadora:
Sociedad Argentina de Biofisica (SAB)
Resumen:
Lipovitellin (LV) is an important lipoprotein present in crustacean eggs, necessary for embryo viability and development. Previously, we have shown that structural changes are coupled to its lipid transfer function. When isolated from eggs at different stages of embryo development, two LV are obtained which differs in the lipid composition but not in the lipid/protein ratio or apoprotein composition (here named LVe and LVl for corresponding to early and late embryo development stages, respectively). Fluorescence spectroscopy, far-UV circular dichroism, partial trypsinolysis and electron microscopy were applied to obtain structural information of these lipoproteins, as well as of partial delipidated states of LVe generated by treatment with phospholipase A2 (LVp) or with triton X-100 (LVt). Completely lipidated LVe and LVl, as well as delipidated forms LVp and LVt maintain both apoprotein components of 94 and 112 kDa. In all the cases, the 112 kDa subunit is more accessible for tryptic cleavage. Only in the case of LVp, more cleavage sites are evident. Secondary structure is similar in LVe and LVl, but partially delipidated LVp and LVt show a small increase in â-sheet at expenses of á-helix. A spheroidal morphology is indicated by negative staining electron microscopy for both LVe and LVl. The spherical shape is not changed by delipidation, although a decreased size is observed, mainly in the case of LVp. Delipidated LVp and LVt were more resistant to denaturation with guanidinium-HCl in comparison with LVe and LVl. Also, acrylamide quenching of tryptophan fluorescence was more efficient in LVe and LVl in comparison with delipidated LVp and LVt. It is concluded that LV stability, shape, and apoprotein conformation is not largely affected by the change in lipid composition during the embryo development, although these properties are dependent on the lipoprotein lipid content.