Enzymes sugar esters

Rich, 1. O., Bedell, B. A., and Dordick, 1. S., Coontrolhng enzyme-catalyzed regi-oselectivity in sugar ester synthesis, BiotechnoL Bioeng., 45, 426 34, 1995. 

Increasing need for regioselective enzyme-catalyzed reactions, e.g., for the selective esterification of di- and multifunctional compounds, the selective hydrolysis of compounds containing multiple ester functions (dicarboxylic acid esters, sugar esters, etc.) and the selective reduction of compounds with multiple carbonyl groups. 

Kennedy, JF Kumar, H Panesar, PS Marwaha, SS Goyal, R Parmar, A Kaur, S. Enzyme-catalyzed regioselective synthesis of sugar esters and related compounds. Journal of Chemical Technology and Biotechnology, 2006, V. 81 (6), 866-876. 

There are two main strategies for the enzyme-catalyzed preparation of sugar esters. The first employs organic solvents similar to those used in chemical synthesis, e.g., DMF, DMSO, and pyridine, which can solubilize both the enzyme and the sugar molecule. The second method involves modification of the sugar followed by solvent free enzyme-mediated esterification. Each of these routes will be discussed in turn below. 

SCHEME 2 Synthesis of pol5merizable sugar esters. The first step is preparation of the sugar monomer via enzyme-mediated synthesis (Alcaligenes sp in p5Tidine) followed by polymerization with a chemical catalyst AIBN in DMF at 60°C. (From Ref. 65.)... 

Synthetic polymers containing sugar branches have attracted considerable interest in recent years. These are typically produced via chemoenzymatic routes where the first step is the enzyme-mediated synthesis of the sugar ester monomer followed by chemical polymerization (Scheme 2). Several workers have developed sugar ester-abased polymers containing vinyl, styrene, acrylamide, etc., functionalities. A discussion of the synthesis methods of these compounds are not in the scope of the current work and interested readers are referred to some recent literature by Patil et al. [64], Kitagawa and Tokiwa [65], and Raku and Tokiwa [66]. 

The application of lipases to the preparation of sugar esters has been reviewed, and a short section with 18 refs, on the formation and hydrolysis of carbohydrate esters is included in a review on the use of esterolytic and lipolytic enzymes in organic synthesis. ... 

Phosphorylase is specific with regard to its action upon < -D-glucose-l-phosphate the / -isomer cannot serve as a substrate for this enzyme. Neither can any other sugar ester be substituted for glucose-l-phosphate. a-L-Glucose-l-phosphate, maltose-l-phosphate, a-D-xylose-l-phosphate could not be polymerized to polysaccharide by potato phosphorylase. - The a-forms of D-mannose-l-phosphate and D-galactose-l-phosphate were not acted upon by muscle phosphorylase. ... 

Several improvements of the process, such as the reaction with acyl chlorides or the application of two-phase reaction systems with propylene glycol and an emulsifier in order to build a microemulsion, have been described in the literature and patents [21]. Another approach for the synthesis of sugar esters is the use of enzymes. Enzymatic catalysis in the field of carbohydrate chemistry has been actively explored over years in laboratory... 

Ionic liquids are promising nonaqueous solvents for the dissolution of carbohydrates and they have been used in several studies on enzymatic sugar ester synthesis. Candida antarctica lipase B was the best enzyme for synthesis of glucose esters in a two-phase system containing an ionic liquid and rm-butanol [31]. Recently, the use of supersaturated sugar solutions [32] and ultrasonic treatment [33] has been reported to make sugar ester synthesis in ionic liquids even more efficient. 

Ward, O. P., Fang, J. and Li, Z. (1997) Lipase-catalyzed synthesis of a sugar ester containing arachidonic acid. Enzyme Microb. Technol., 20, 52-56. 

Esterification. The hydroxyl groups of sugars can react with organic and inorganic acids just as other alcohols do. Both natural and synthetic carbohydrate esters are important in various apphcations (1,13). Phosphate monoesters of sugars are important in metabohc reactions. An example is the enzyme-catalyzed, reversible aldol addition between dibydroxyacetone phosphate [57-04-51 and D-ylyceraldehyde 3-phosphate [591-57-1 / to form D-fmctose 1,6-bisphosphate [488-69-7],... 

Furthermore, the GPO procedure can also be used for a preparative synthesis of the corresponding phosphorothioate (37), phosphoramidate (38), and methylene phosphonate (39) analogs of (25) (Figure 10.20) from suitable diol precursors [106] to be used as aldolase substrates [102]. In fact, such isosteric replacements of the phosphate ester oxygen were found to be tolerable by a number of class I and class II aldolases, and only some specific enzymes failed to accept the less polar phosphonate (39) [107]. Thus, sugar phosphonates (e.g. (71)/(72)) that mimic metabolic intermediates but are hydrolytically stable to phosphatase degradation can be rapidly synthesized (Figure 10.28). 

Phosphonate analogs to phosphate esters, in which the P—0 bond is formally replaced by a P—C bond, have attracted attention due to their stability toward the hydrolytic action of phosphatases, which renders them potential inhibitors or regulators of metabolic processes. Two alternative pathways, in fact, may achieve introduction of the phosphonate moiety by enzyme catalysis. The first employs the bioisosteric methylene phosphonate analog (39), which yields products related to sugar 1-phosphates such as (71)/(72) (Figure 10.28) [102,107]. This strategy is rather effective because of the inherent stability of (39) as a replacement for (25), but depends on the individual tolerance of the aldolase for structural modification close... 

Enzymes can be used to specifically modify the pectins. Pectin methyl esterase is already widely used to adjust the gelling properties of commercially available pectins. The acetyl esters also strongly affect the gelation [2,3] and removal is important for the upgrading of sugar beet pectin, extractable from a by-product of the sugar industry. 

Potentiometric enzyme-based electrodes have found application in clinical, pharmaceutical, food and biochemical analyses to enable the selective determination of a wide range of important enzyme substrates, including amino acids, esters, amides, acylcholines, /Mactam antibiotics, sugars, enantioselective drugs and many others [74]. 

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