ChemInform Abstract: Regioselective Deacetylation of Disaccharides via Immobilized Aspergillus niger Esterase(s)-Catalyzed Hydrolysis in Aqueous and Non-aqueous Media (original) (raw)
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Screening of lipases for regioselective hydrolysis of peracetylated β-monosaccharides
Journal of Molecular Catalysis B: Enzymatic, 2007
The monodeacetylation of peracetylated--d-galactose (1) and peracetylated N-acetyl--d-glucosamine (2) by different lipases is here described. Lipases from different sources in an immobilized form were evaluated to find those that offer the higher activity and regioselectivity in the reactions. In the hydrolysis of 1, the lipase from Aspergillus niger was the most active one, although it hydrolyzed the anomeric position. Using the lipase from Candida rugosa, 30% yield of the corresponding 6-OH isomer was achieved. On the other hand, in the hydrolysis of 2, the lipase from A. niger was the most active and regioselective catalyst, producing more than 75% of the 6-OH derivative product.
Advanced Synthesis & Catalysis, 2007
The effect of the immobilization strategy on the activity, specificity and regioselectivity of three different lipases [those from Thermomyces lanuginose (TLL), Aspergillus niger (ANL) and Candida antarctica B (CAL-B)] in the hydrolysis of peracetylated b-monosaccharides has been evaluated. Three very different immobilization strategies were utilized, covalent attachment, anionic exchange and interfacial activation on a hydrophobic support. The octyl-TLL immobilized preparation was the most efficient biocatalyst in the hydrolysis of 1,2,3,4,6-penta-O-acetyl-b-d-galactopyranose, producing specifically 6-hydroxy-1,2,3,4-tetra-O-acetyl-b-d-galactopyranose in 95 % overall yield, whereas the CNBr-TLL preparation was 48 times slower and regioselective towards the anomeric position, producing the 1-hy-droxy derivative in 70 % yield. The PEI-TLL immobilized preparation was the most efficient catalyzing the hydrolysis of 1,2,3,4,6-penta-O-acetyl-b-d-glucopyranose, permitting us to obtain up to 70 % of the 6-hydroxy product. In the hydrolysis of 2-acetamido-2-deoxy-1,3,4,6-tetra-O-acetyl-b-d-glucopyranose, the octyl-CALB preparation was not selective at all for the production of monohydroxy products whereas when CAL-B was immobilized on PEI-agarose, the enzyme was highly specific and regioselective producing the 6-hydroxy-2-acetamido-2-deoxy-1,3,4-tri-O-acetyl-b-d-glucopyranose in 70 % yield.
Journal of Biotechnology, 2002
Enzymatic synthesis of fatty acid esters of di-and trisaccharides is limited by the fact that most biological catalysts are inactivated by the polar solvents (e.g. dimethylsulfoxide, dimethylformamide) where these carbohydrates are soluble. This article reviews the methodologies developed to overcome this limitation, namely those involving control over the reaction medium, the enzyme and the support. We have proposed the use of mixtures of miscible solvents (e.g. dimethylsulfoxide and 2methyl-2-butanol) as a general strategy to acylate enzymatically hydrophilic substrates.
Carbohydrate Research, 2002
In a reaction medium mixture of 9:11 t-BuOH and pyridine (v/v) the effect of fatty acid chain length (C-4-C-12) on C. antarctica lipase B (Novozym 435, EC 3.1.1.3) catalysed esterification was studied. a and b maltose 6%-O-acyl esters in an anomeric molar ratio of 1.0:1.1 were synthesised independently of the chain length, but the initial specific reaction rate increased with decreasing chain length of the acyl donor. The product yield followed the same trend with a lauryl ester yield of 1.1% (mol/mol) and a butyl ester yield of 27.6% (mol/mol) after 24 h of reaction. With sucrose as the acyl acceptor the 6%-O-acyl and 6-O-acyl monoesters were formed with fatty acids of chain length C-4 and C-10 while the 6%,6-O-acyl diester was formed only with butanoic acid (C-4:0) as acyl donor. The 6%-O-acyl and 6-O-acyl monoesters and the 6%,6-O-acyl diester of butanoic acid were produced in a molar ratio of 1.0:0.5:0.2 and with decanoic acid (C-10:0) the 6%-O-acyl and 6-O-acyl monoesters were formed in the ratio of 1.0:0.3. The highest initial reaction rate and yield were obtained with the shortest chain length of the acyl donor. Initial reaction rates and ester yields were affected by the solubility of the disaccharide, with higher reaction rates and yields with maltose than with sucrose, while no formation of esters were observed with either cellobiose or lactose as acyl acceptors.
Enzymatic Synthesis of Oligosaccharides: A Powerful Tool for a Sweet Challenge
Current Organic Chemistry, 2013
Carbohydrates are complex and structurally diverse compounds in nature with key roles in a broad range of life processes including signal transduction, carcinogenesis and immune responses. Many natural products contain oligosaccharides that are vital for their biological activity. Despite ongoing challenges, tremendous progresses have been made in recent years for the synthesis of carbohydrates. The chemical glycosylation methods have become more sophisticated and the synthesis of oligosaccharides has become more predictable. Nonetheless, thanks to their straightforward stereoselectivity and efficiency, carbohydrate-processing enzymes follow being a powerful practical alternative in a wide set of synthetic applications targeted to the obtainment of natural oligosaccharides, glycoconjugates and their analogues. In this review, recurring to many practical examples, a general updated overview of the behavior, the advantages and the drawbacks related to the application of glycosyltransferases, glycosylhydrolases and glycosynthases in the oligosaccharide synthesis will be provided.
Enzymatic regioselective deprotection of peracetylated mono- and disaccharides
1999
Selective enzymatic hydrolysis of the peracetylated disaccharides, namely cellobiose, lactose, maltose and melibiose, with lipase from Asperilligus niger in aqueous buffer and organic solvent for 30 min afforded exclusively the corresponding heptaacetates with a free hydroxyl group at C-1 in high yield. Prolonged reaction of the b-1,4 linked cellobiose and lactose peracetates afforded selectively their hexaacetates with free hydroxyl groups at C-1,2, whereas the a-1,4 linked disaccharides maltose and melibiose peracetate gave a complex mixture of products. The reaction of 2-acetamido-2-deoxy-1,3,4,6-te-Ž . tra-O-acetylglucopyranose 11 for 22 h afforded as the major product the diacetate 12 with free hydroxyl groups at C-1,4. q
Lecitase® ultra as regioselective biocatalyst in the hydrolysis of fully protected carbohydrates
Journal of Molecular Catalysis B: Enzymatic, 2008
This paper shows that Lecitase Ultra is an enzyme preparation with a great interest as regioselective biocatalyst in the deprotection of 4 different peracetylated sugars: 1,2,3,4,6-penta-O-acetyl--d-galactopyranose (1), 2-acetamido-2-deoxy-1,3,4,6-tetra-O-acetyl--d-glucopyranose (4), 1,2,3,4,6-penta-O-acetyl-␣-d-mannopyranose (7) and 2,3,4,6-tetra-O-acetyl--d-galacto pyranosyl-(1 → 4)-1,2,3,6-tetra-O-acetyl--dglucopyranoside (9). The enzyme properties (specificity, preference for the per-acetylated sugar and regio-selectivity) were strongly modulated by the immobilization conditions, for example the octyl-LECI preparation was 10 fold more active than the PEI-LECI preparation, while it was more than 40 fold less active against some other substrates. Very interestingly, these changes also affected the regioselectivity, depending on the preparation used it was possible to get free OH groups in anomeric position, position 6 or the mixture of both. Finally, the octyl-LECI preparation did not recognize the ␣-sugars, favouring the -isomers (in opposition to most commercial lipases or the other LECI preparations). This is potentially useful to obtain pure ␣-peracetylated monosaccharides from a mixture of anomers.