Dye-ligand membranes as selective adsorbents for rapid purification of enzymes: a case study

A new adsorbent for the selective binding of enzymes, in the form of microporous membranes carrying triazine dyes as pseudo-affinity ligand, has been implemented in the recovery of glucose-6-phosphate dehydrogenase from yeast. A detailed investigation of the process parameters has been performed. In the adsorption step, the contact time for binding G6PDH could be reduced down to 0.25 s without significant decrease of the capture efficiency. Hence, fast filtration allowed to isolate G6PDH from a dilute extract (1.6 mug G6PDH . mL(-1)), where the enzyme accounted for 1% of the proteins. The yield of the selective elution step using NADP was only 70% at best. It could be improved to near 100% by supplementing the eluent with ethylene glycol, without loss of selectivity. A Scale-up of the cross-section of the membrane by a factor of 40 allowed to purify 1140 U from 0.6 L extract from 1% to 57% purity with 82% yield, within 10 minutes. The case study presented here demonstrates the applicability of general-purpose membrane adsorbents for the purification of enzymes.