Evaluation of affinity precipitation and a traditional affinity Chromatographic procedure for purification of soybean lectin, from extracts of soya flour

Abstract

Soya meal of different mean particle sizes were produced by grinding soybeans in a mill with exchangeable screens. The surface area of each flour was calculated based on sieving experiments. Protein extracts were obtained from the different flour preparations and as the last stage in a purification process for soybean lectin (SBH), the extracts were passed over an affinity column with N-acetyl- D-galactosamine ( d-GaNAc) as a ligand. The yield of SBH bound and eluted was studied with regards to the particle size distribution in the soya meal used as the source material. Purification of the protein was also studied by affinity precipitation using N-aminophenyl- D-GalNAc coupled to the reversibly soluble—insoluble polymer Eudragit S-100, in order to evaluate how well this method can compare with a traditional purification method of SBH. The recovery of lectin isolated by affinity precipitation was less than the amount purified by affinity chromatography, using the same ammonium sulphate fractionated extract as starting material. The affinity precipitation technique was also used for isolation of SBH directly from untreated protein extracts.