Physicochemical characterization of golden snail (Pomacea sp.) lectin
2001
Asnani, A. | Merca, F.E. (Philippines Univ. Los Banos, College, Laguna (Philippines). Inst. of Chemistry)
A Ca sub 2+ dependent lectin was isolated from the visceral region of golden snail by protein extraction using Tris Buffered Saline (TBS), 0-25% ammonium sulfate fractionation, and column chromatography using gel filtration on Sephadex G-200 followed by Superose-12. Affinity chromatography with fetuin-agarose column was employed for single step purification. The lectin was present at a concentration 0.25 mg/g visceral region. An electrophoretically homogeneous form was obtained from Superose-12 column. The apparent molecular weight of the lectin in its native form was estimated by gel filtration analysis to be approximately 860 kDa. On SDS [sodium dodecyl sulphate]-gel electrophoresis at pH8.8, a single band corresponding to a 210 kDa protein was observed. This result suggests the possibility that golden snail lectin consists of four sub units of the same molecular weight. From the sedimentation equilibrium experiment, absorption coefficient of the golden snail revealed to be 0.34 at 280 nm whereas the partial specific volume of golden snail lectin was 0.732 ml.g as calculated from its amino acid composition. Binding specificity of golden snail on a fetuin-modified sensor surface indicated a monovalent interaction between the lectin and its carbohydrate specific, fetuin, with the pseudo-first order rate constant (K sup obs) 0.0585 sub-1
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