Wheat β-amylase behaviour regarding salt promoted adsorption processes

Summary

The behaviour of wheat β-amylase from crude extracts in chromatography on agarose gels substituted with different ligand types was investigated. The enzyme displayed high salt promoted adsorption onto thiophilic gels provided with sulfone-thioether and 2-thiopyridine ligands. Quantitative recovery of the enzyme was easily accomplished by elution with buffer in the absence of Na₂SO₄. The 3-(2-pyridylthio)-2-hydroxypropylagarose (PyS-gel) also allowed elimination of pigments present in the wheat extract. These pigments showed no adsorption onto the gel, thus regeneration is easily achieved, allowing its re-use.

The enzyme also displayed strong salt-dependent adsorption onto adsorbents provided with pyridyldisulfide moieties, but in this case enzyme binding was due to its thiol content since elution was achieved mainly through reduction with DTT.

When the enzyme was chromatographed on a series of hydrophobic alkyl ligands in the presence of 0.5 M sodium sulphate, it was partially adsorbed on pentylagarose and quantitatively adsorbed on hexyl-agarose, elution being easily performed by sodium sulphate-free buffer. This behaviour was markedly different from that towards phenyl-Sepharose, to which the enzyme was strongly adsorbed and which required much more drastic elution conditions.