Enzymes aggregation

The most effective of these include immobilization [80], lipid coating [81], surfactant coating [82], use of cross-linked enzyme crystals [83], cross-linked enzyme aggregates [84], and membrane reactors [85]. 

Immobilized enzymes, particularly LAC, have been employed in the degradation of triclosan. The immobilization of LAC from Coriolopsis polyzona through the formation of cross-linked enzyme aggregates (CLEAs) and their subsequent use in an FBR for the removal of endocrine disrupting compounds [42] produced the complete removal of triclosan, nonylphenol, and bisphenol A (5 mg L-1 each) at a HRT of 150 min. The application of CLEAs in a perfusion basket reactor [43]... 

Effective and simple immobilization of enzymes can be obtained by the cross-linking of enzyme aggregates, so-called CLEAs [55]. In this way, essentially any enzyme, including crude preparations, can be transformed into a heterogeneous type of material, insoluble in both water and organic solvents, that is stable and recyclable with high retention of the enzyme s original activity [56], These enzyme preparations are, therefore, of special value for both bio-bio and bio-chemo cascade processes. 

Mateo, C., Palomo, J.M., van Lancen, L.M., van Rantwijk, E. and Sheldon, R.A., A new, mild cross-linking methodology to prepare cross-linked enzyme aggregates. Biotech. Bioeng., 2004, 86, 273-276. 

Oligomers or enzyme aggregates are often more stable than the eonstituent monomers. Based on this idea of protein-protein interaetions, Shami, Rothstein and Ramjeesingh (1989) have proposed a new approaeh to stabilization using antibodies speeifie for the enzyme. 

The 3-pyridinecarboxyaldehyde 58 is highly water soluble, and so the spontaneous cyanide addition to give racemic cyanohydrin cannot be suppressed unless the aqueous pH is lowered below 3.5, which is not tolerated by the enzymes. The only available option is to operate in a 100% organic solvent system. This was recently made possible by the availability of the cross linked enzyme aggregate particles (CLEAs), which can tolerate organic solvents [64]. The individual precipitated protein molecules are chemically bonded to one another through the formation... 

Hayzer, D.J. Moses, V. The enzymes of proline biosynthesis in Escherichia coli. Their molecular weights and the problem of enzyme aggregation. Biochem. J., 173, 219-228 (1978)... 

None of the detailed mechanisms to be discussed considers the macro-molecular association that may be involved in the action of RNase on high molecular weight polyribonucleotides. Preiss reported from light scattering studies that very large RNA-enzyme aggregates may be formed (393). Their significance for the catalytic mechanism is unknown. 

Cao, L., van Rantwijk, F. and Sheldon, R.A. (2000) Cross-linked enzyme aggregates a simple and effective method for the immobilization of penicillin acylase. Org. Lett., 2, 1361. 

Sheldon, R.A., Schoevaart, R. and van Langen, L.M. (2006) Cross-linked enzyme aggregates. Meth. Biotechnol., 22, 31. 

Sheldon, R.A., Sorgedrager, M.J. and Janssen, M.H.A. (2007) Use of cross-linked enzyme aggregates (CLEAs) for performing biotransformations. Chim. Oggi — Chemistry Today, 25, 62. 

Cross-linked CPO aggregates in the pores of mesocellular foams The CPO-CLEAs (cross-linked enzyme aggregates) supported in mesocellular foams were more stable against leaching than conventional catalysts prepared by physical adsorption of CPO on the same support [10]... 

Perez DI, Van Rantwijk F, Sheldon RA (2009) Cross-linked enzyme aggregates of chloroperoxidase synthesis, optimization and characterization. Adv Synth Catal 351 2133-2139... 

Immobilization of Enzymes Cross-linked Enzyme Aggregates (CLEAs) 405... 

However, the relatively high enzyme costs form an obstacle to commercialization. Inefficient laccase use is a result of its instability towards the oxidizing reaction conditions. We have recently shown that the stability of the laccase under reaction conditions can be improved by immobilization as a cross-linked enzyme aggregate (see Chapter 9). It has also been shown that a water-soluble iron complex of a sulfonated phthalocyanine ligand is an extremely effective catalyst for starch oxidation with hydrogen peroxide in an aqueous medium [11]. 

Entrapment of enzymes and cells has played an important role in developing bioprocesses. Applications of entrapment technology to biosensors and bioanalysis have mainly been focused on udlizadon of cells and, to a smaller extent, on enzymes (24). Combining covalent coupling and entrapment cross-links enzymes and inert protein to form a protein membrane that covers the sensitive part of the electrode dp in bioanalytical applications (25). Entrapping enzyme aggregates is another variadon of this methodology (26). 

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