| 摘要 |
<p>A novel method for immobilizing enzymes, while still keeping them in solution (thus under conditions of homogeneous catalysis), is reported. It consists in blocking enzymes in between two isoelectric membranes, having isoelectric points (pI) on either side of the pI of the enzyme to be 'trapped'. The reactor consists on a multichamber electrolyzer, in which the electric field is coupled to a hydraulic flow for continuously recycling the enzyme inside and outside the electric field to reservoirs acting as both heat exchangers and as feeders for injecting (or collecting) substrates, cofactors and other reagents. The pH of optimum activity is maintained by co-immobilizing the buffers within the enzyme reaction chamber. This is achieved by selecting appropriate amphoteric buffers, having a pI value comprised between the pI of the two membranes keeping the enzyme isoelectric and possessing a reasonable buffering power at their respective pIs. The enzyme can be further stabilized by adding to the reactor polyols (e.g., ethylene glycol, glycerol, erythritol, xylitol, sorbitol), polymers (e.g., dextrans, polyethylene glycol), carbohydrates (e.g., sucrose, lactose, mannitol). Said reactors maintain the characteristic parameters (Km and Ki) of the free enzyme and have the advantage of permitting a continuous infusion (or harvesting) of substrates, cofactors and/or other charged reagents. Comprised in the invention is also the possibility of transporting electrically also neutral substances, via complex formation or via adsorption within charged micelles.</p> |
