Studies on blood group substances. V. Blood group substance A coupled to agarose as an immunosorbent

Desorption of immunoglobulins from Protein A-Sepharose CL-4B under mild conditions

Conditions which permit the dissociation of IgG-staphylococcal protein A interactions without resort to low pH buffers or the use of chaotropic ions are discussed in relation to: (a) the mechanism of the binding reaction; (b) the use of immobilised protein A for purification of cells or removal of immune complexes from serum. Glycyl-tyrosine, glycyl-histidine, glycyl-phenylalanine and tryptophan, representing the class of competing ligand desorbents, and ethylene glycol, an agent which disrupts hydrophobic interactions, were found to be the best desorbents.

Separation of anti-dinitrophenyl antibodies according to affinity by fractionated elution from immunoadsorbent using thiocyanate

The possibility of fractionating anti-DNP-antibodies according to their affinity by successive elution from a DNP-immunoadsorbent with increasing concentrations of thiocyanate (KSCN) was investigated. Using KSCN at molarities of 0.5 M, 2.0 M and 3.0 M in a stepwise elution procedure, the mean affinity of the eluted antibody fractions was found to increase with increasing molarity of the eluent. The method described is a simple, reliable means of separating antibodies on an affinity basis which is of special value in systems where haptens are not available.

A simple procedure for the isolation of L-fucose-binding lectins from Ulex europaeus and Lotus tetragonolobus

L-Fucose-binding lectins from Ulex europeaus and Lotus tetragonolobus were isolated by affinity chromatography on columns of L-fucose-Sepharose 6B. L-Fucose was coupled to Sepharose 6B after divinyl sulfone-activation of the gel to give an affinity adsorbent capable of binding more than 1.2 mg of Ulex lextin/ml of gel, which could then be eluted with 0.1M or 0.05M L-fucose. Analysis of the isolated lectins by hemagglutination assay, by gel filtration, and polyacrylamide disc-electrophoresis revealed the presence of isolectins, or aggregated species, or both. The apparent mol. wt. of the major lectin fraction from Lotus was 35000 when determined on Sephadex G-200 or Ultrogel AcA 34. In contrast, the apparent mol. wt. of the major lectin fraction from Ulex was 68 000 when chromatographed on Sephadex G-200 and 45 000 when chromatographed on Ultrogel AcA 34. The yields of lectins were 4.5 mg/100 g of Ulex seeds and 394 mg/100 g of Lotus seeds.