Marine algal lectins: new developments

Abstract

Lectins can be extracted more readily from marine algae if the plant material is freeze-dried or frozen in liquid nitrogen prior to homogenisation. The addition of detergents, such as Tween 80, to the extraction medium and diluents, enhances extraction and detection of the lectins. Marine algal lectins can be isolated by affinity chromatography using a general affinity complex such as yeast mannan-Cellulofine which facilitates the isolation of purified lectin for biochemical characterisation. Red algal lectins exist as three types: low molecular weight molecules which bind glycoproteins, but not monosaccharides and have no requirement for divalent cations; lectins which bind monosaccharides and related small molecules,but have no divalent cation requirements; larger lectins (M.W. > 64000) which bind monosaccharides in the presence of divalent cations. No green algal lectin characterised so far requires divalent cations for haemagglutination. Possibly, only green algal lectins capable of forming oligomers have the capacity to bind monosaccharides.