Esterolytic enzyme

Reactions on macromolecular precursors are most often the key step in the synthesis of sophisticated polymers in various well documented fields of steadily increasing importance such as a) linear or crosslinked polymeric reagents and catalysts (2,5,6, 49) b) polymers showing esterolytic enzyme-like properties (2, 49-52) c) polymeric drugs (53.54) and so on... Three more specific but still highly significant studies are outlined below. 

Typical antibody-catalyzed reaction rates are several hundredfold to 100,000-fold faster than the uncatalyzed reaction of the substrate. Several fundamental postulates have been proposed to explain the rate enhancements that nevertheless fall short of the enormous rate accelerations of enzymes. Is activity truly due solely to transition state stabilization by antibody-binding interactions Can additional binding interactions be built into the combining site or into the substrate molecule itself to increase the overall rate of the reaction Can new screening methods and immunological methods be developed to uncover novel catalysts with diverse activities Most important, can novel esterolytic catalysts be developed based on currently available catalytic antibody technology to efficiently hydrolyze and detoxicate cocaine ... 

Li, Y.-F., and Hammerschmidt, F., Enzymes in organic chemistry. Part 1. Enantioselective hydrolysis of a-(acyloxy iphosphonates by esterolytic enzymes, Tetrahedron Asymmetry, 4, 109, 1993. Benayoud, F and Hammond, G.B., An expedient synthesis of (a,a-difluoroprop-2-ynyl)phosphonate esters, J. Chem. Soc., Chem. Commun., 1447, 1996. 

Several reviews have been published describing our work on imidazole catalysis.(1-4) Other investigators in this field have published comprehensive review articles comparing synthetic catalysts to enzymes.(5-91 The esterolytic activity of the three catalyst systems reviewed in this paper have been compared to poly[4(5)-vinylimidazole] (PVIm) in 28.5% ethanol-water solutions since PVIm is not soluble in water. However, within each system, minor changes in catalyst apolarity illustrate the effect of hydrophobic interactions on the rate of esterolysis. The substrates consisted of a series of neutral j -nitrophenyl esters (Sn) and negatively charged 4-acyloxy-3-nitrobenzoic acids (Sn ), where n denotes the number of carbons in the acyl chain. 

Phospholipases are crucial enzymes in the arachidonic acid pathway and appear to be primarily responsible for the esterolytic action that releases arachidonic acid from phospholipids (209). Once released, this acid is converted into several mediators of inflammation. The PLA2 s are small (MW 14,000) stable proteins that require Ca2 + ions for the specific hydrolysis of the 2-acyl group of 3-sn-phospholipids. 

Use of Enzymes. The big advantage of enzyme applications is their well-known specificity in reaction pathways. A survey in the biotechnological use of enzymes showed that 65 % of all reported applications fell into the classes of esterolytic reactions (40%) and dehydrogenase reactions (25 %) pig liver esterase, pig pancreatic lipase, the lipase from Candida cylindracea and baker s yeast being the most frequently used biocatalysts (35). For the generation of C 13-aroma volatiles, however, two additional enzyme systems have gained importance, (i) hydrolases and... 

The lipolytic/esterolytic activity of Lactobacillus has also received limited attention. An esterase of Lb. plantarum was purified by Oterholm et al. (1972) who found that the enzyme was maximally active at pH 6.7 and... 

Esterolytic and Lipolytic Enzymes in Organic Synthesis. Boland. W. Frdssl. C, Lorenz. M. Synthesis 1991, 1049. 

Complementary to the use of isolated enzymes, whole microbial cells have also been used to catalyze esterolytic reactions. Interesting cases are reported from bacteria, yeasts, and fungi, such as Bacillus subtilis [249], Brevibacterium ammo-niagenes [250], Bacillus coagulans [251], Pichia miso [26], and Rhizopus nigricans [252]. Although the reactirMi control becomes more complex on using whole microbial cells, the selectivities achieved are sometimes impressive. This was shown by the successful resolution of a secondary alcohol via hydrolysis of its... 

Partial sequences of homologous proteolytic (Al and esterolytic (B) enzymes from the region about the active serine residue ... 

Griswold, K. E. pH sensing agar plate assays for esterolytic enzyme activity. Methods Mol. Biol. 2003, 230, 203-211. 

It has been recognized a long time ago that hydrolytic enzymes can behave as any other catalyst and catalyze the reverse reaction condensation (1,2). It is then possible to use simple enzymes with esterolytic activity, not requiring cofactors, such as esterases, lipases, or some proteases, to synthesize ester bonds, as long as the thermodynamic conditions required to favor this reaction are not detrimental to the activity of the enzyme. This last point is of great importance since most enzymes have evolved to operate in aqueous media, and not in the conditions necessary to foster condensation, for example, low water and high acid and/or... 

It is of particular interest to note that the slow release of ethanol is observed in the presence of lipase, an esterolytic enzyme, even in neutral water (Fig, 10), while in the presence of pronase, a proteolytic enz3nne, no release of ethanol takes place. 

Polymeric imidazole catalysts are the synthetic prototype of esterolytic enzymes because, like the enzymes, they have binding centers for the substrate as well as for the catalytic groups. In case of the homopolymer, polyvinylimidazole, the partially protonated groups can act as binding sites, provided the substrate is negatively charged. Thus at pH 7.5, when... 

During the last year Tsai was able to demonstrate the esterolytic activity (15) of LADH using octanoate esters as substrates (the ability of this enzyme to catalyse a given reaction generally increases with the chain length of the substrate to reach a maximum at eight carbon atoms). The esterase activity, assayed following... 

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