CLEAs

Diketene (635) is converted into 3-phenyl-3-butenoic acid (636) by the reaction of phenylzinc, magnesium, and aluminum reagents via C—O bond clea-vage[495j. 

Solution 2-Methyl-3-pentanol, an open-chain alcohol, has M+ = 102 and might be expected to fragment by o- cleavage and by dehydration. These processes would lead to fragment ions of m/z = 84, 73, and 59. Of the three expected fragments, dehydration is not observed (no m/z = 84 peak), but both a clea iges take place (m/z = 73, 59). 

Durrell, Lawrence. The Alexandria Quartet... Justine. Balthazar. Mountolive. Clea. (With revisions.). London Faber, 1962. 884p. 

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]... 

Enzymatic degradation was tested with commercial LAC from M. thermophila (2,000 U L ). E2 and EE2 were completely degraded even in the absence of mediators after 3 and 5 h, respectively, and after 1 h in the presence of some mediators. For El total removal was achieved in 8 h in the presence of VA and >70% for the other mediators after 24 h, whereas elimination reached 65% in the absence of mediators [8]. The immobilization of this enzyme by encapsulation in a sol-gel matrix [58] was employed for the treatment of a mixture of El, E2, and EE2 both in a batch stirred tank reactor (BSTR) operating in cycles and a continuous PBR. Removal of estrogens was >85% in the BSTR and 55%, 75%, and 60% for El, E2, and EE2, respectively, in the PBR. Both systems were able to reduce the estrogenic activity of the mixture in 63%. Likewise, the immobilization of VP in the form of CLEAs completely removed E2 and EE2 within 10 min from batch experiments, with a concomitant reduction of estrogenic activity, higher than 60% for both compounds [44]. 

VP from B. adust a enzyme Flask scale with CLEAs... 

The iron(III) complexes FeL33+, where L = 2,21-bipyridine and various substituted 1,10-phenanthrolines, cleave a variety of or-ganometals in acetonitrile according to the general reaction mechanism in Scheme I (6). The activation process for oxidative clea-... 

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. 

ETHER CLEA VAGE REACTION LEADING TO POLY(ETHER ESTER) RESINS... 

Citrate buffer (0.1 m, pH 2.5, 20 /iL), 3-pyridinecarboxaldehyde (300 mg) and CLEA -immobilized HNL (40 mg) were added to 9.7 mL of the dichloromethane-HCN solution and the reaction was aged for 2-20 h at 5 °C. Commercially available CLEAS of almond HNL (PaHNL-CLEA ) and cassava HNL (MeHNL-CLEA ) were used to catalyze the syntheses of R)- and (5)-cyanohydrin respectively. 

The use of CLEA preparations of commercially available HNLs allowed for the enantiocomplementary production of cyanohydrins from a pyridinecarboxaldehyde at a much higher chiral purity than had previously been demonstrated with any chemical catalyst. The key to the success of this process was the use of the CLEA -immobilized biocatalysts that allowed reaction conditions to be chosen to minimize the negative effects of the nonspecific background reaction. 

Zalipsky S, et al. New detachable poly(ethylene glycol) conjugates cysteine-clea-vable lipopolymers regenerating natural phospholipid, diacyl phosphatidyletha-nolamine. Bioconj Chem 1999 10 703. 

GEN.257.1. Prigogine, Einstein and Magritte. A study of creativity, Conference, Einstein Meets Magritte, CLEA, VUB, mai 1995 public en 1999 in Einstein Meets Magritte, Kluwer, Dordrecht, pp. 99-105. 

Both acylation and deacylation can be performed with a lipase as shown in Scheme 6.9 in which a CALB CLEA was used in the deacylation step that, not surprisingly, was rather slow compared to deacylation with pen acylase. 

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