Carbohydrate characterization of an egg carotenoprotein from the snail pomacea scalaris

ITUARTE S,; DREON MS,; FERNÁNDEZ PE,; HORACIO HERAS; POLLERO RJ,

Rosario

Congreso; XLII Reunión conjunta SAIByBM y Soc. Argentina de Neurociencias (SAN); 2006

Invertebrate carotenoproteins are a diverse group of proteins still poorly characterized. In molluscs, ovorubin (OR) from Pomacea canaliculata is the only carotenoprotein well studied, showing no similarities with any known invertebrate carotenoprotein. The recently isolated carotenoprotein from P. scalaris eggs, named scalarin (SC) seems to be structurally and functionally related to OR. The aim of this work was to further characterize SC to understand carotenoprotein variability in this group. In particular, the carbohydrate moiety and its influence on particle size and shape were studied. SC was isolated from egg homogenates by ultracentrifugation and size exclusion chromatography (SEC). Carbohydrate characterization was performed by determining the total content, composition by GLC and oligosaccharide moieties by lectin analysis onto dot blotted proteins. We determined the molecular weight of the glycoprotein by PAGE, SEC and small angle X ray scattering (SAXS). SC contains mannose as the major carbohydrate. Five lectins, including ConA, WGA and JAC bound SC oligosaccharides, indicating the presence of N-linked oligosaccharides with high mannose and hybrid type cores, as well as O-linked moieties with a core containing substituted T antigens. MW estimation differed from 300-500 KD, depending on the analytical technique employed, probably due to the 20% carbohydrate content.