Lipases application

We have made a number of wax esters by this technique in a stirred batch reactor under vacuum, thus demonstrating one of many important practical aspects of lipase applications. 

Lipases (triacylglycerol hydrolases, EC 3.1.1.3) are enzymes that catalyze reactions such as hydrolysis, interesterification, esterification, alcoholysis, acidolysis, and aminolysis [1]. There is an increasing interest in the development of lipase applications to oleochemical transformations to obtain esters of long-chain fatty acids, as monoalkyl esters of fatty acids [2]. Utilization of lipase as a catalyst for the production of biodiesel, defined as a mixture of monoalkyl esters, is a clean technology due to its nontoxic and environmental fnendly nature, requiring mild operating conditions compared with chemical method [3]. 

Some other miscellaneous applications of lipases have bee reported, including their use in diagnostics and biosensors (Hasan et al. 2006). A comprehensive analysis of lipase applications can be found in http //www.au-kbc. org/beta/bioproj2/index. html. 

Another example of lipase application in biomass valorization is the synthesis of monoester derivatives of 6-azauridine via one-step regioselec-tive acylation. It is catalyzed by immobilized lipase (CAL-B) where 99% of the substrate was converted with 99% selectivity into target product... 

MICROEMULSION-BASED ORGANOGELS CONTAINING LIPASE APPLICATION IN THE SYNTHESIS OF ESTERS Pastou A Stamatis H Xenakis A National Hellenic Research Foundation... 

Pastou, A., Stamatis, H., Xenakis, A. 2000. Microemulsion-based organogels containing lipase Application in the synthesis of esters. Prog. Colloid Polym. Sci. 115, 192-195. 

Arantes V, Saddler JN (2010) Acess to cellulose limits the efficiency of enzymati-chydrolysis the role of amorphogenesis. Biotechnol Biofuels 3 4-12 Aravindan R, Anbumathi P, Viruthagiri T (2007) Lipase applications in food industry. Indian J Biotechnol 6 141—158... 

Lipases as acylation catalysts, mechanism and preparative applications, particularly in heterocyclic chemistry 98AG(E)1608. 

Alkanolamides from fatty acids are environmentally benign surfactants useful in a wide range of applications. It was found that most lipases catalyze both amidation and the esterification of alkanolamides however, normally the predominant final products are the corresponding amides, via amidation, and also by esterification and subsequent migration [15]. Recently, an interesting example for the production of novel hydroxyl-ated fatty amides in organic solvents has been carried out by Kuo et cd. [16]. 

Sample Collection and Enzyme Stability. Serum samples are collected with chemically clean, sterile glassware. Blood is allowed to clot at room temperature, the clot is gently separated from the test tube with an applicator stick, and the blood is centrifuged for 10 minutes at 1,000 g. If the red cells are known to contain the enzymes whose activity is being measured, as in the case of LD, even slightly hemolyzed serums must be discarded. When acid phosphatase is to be measured, the serum should be placed immediately in ice and processed as soon as possible, or it should be acidified by the addition of a small amount of sodium citrate. Anticoagulants such as EDTA, fluoride and oxalate inhibit some serum enzymes. However, heparin activates serum lipoprotein lipase. 

Recently Shihabi and Bishop (93) described a refinement in the preparation of a stable substrate and demonstrated the feasibility monitoring the reaction kinetically. This procedure has been evaluated by Lifton et. al. (9 ), who found that this method correlated well (r 0.914) with the copper soap-lipase method of Dirstine. They concluded that the method was rapid (less than 5 min. per sample), accurate, precise and linear over a clinically useful range. Its simplicity allows its application as an emergency procedure. Attempts to use this assay for urine lipase activity were unsuccessful. 

The use of ionic liquids (ILs) to replace organic or aqueous solvents in biocatalysis processes has recently gained much attention and great progress has been accomplished in this area lipase-catalyzed reactions in an IL solvent system have now been established and several examples of biotransformation in this novel reaction medium have also been reported. Recent developments in the application of ILs as solvents in enzymatic reactions are reviewed. 

An IL solvent system is applicable to not only lipase but also other enzymes, though examples are still limited for hpase-catalyzed reaction in a pure IL solvent. But several types of enzymatic reaction or microhe-mediated reaction have been reported in a mixed solvent of IL with water. Howarth reported Baker s yeast reduction of a ketone in a mixed solvent of [hmim] [PFg] with water (10 1) (Fig. 16). Enhanced enantioselectivity was obtained compared to the reaction in a buffer solution, while the chemical yield dropped. 

In the lipase-catalyzed resolution, temperature control of enantioselectivity has been generally accepted for its simplicity and theoretical reliability. Lowering the reaction temperature usually enhances the enantioselectivity. Here, the historical and theoretical backgrounds of the temperature control of enantioselectivity and its applicability to the method are described. Recent literatures for the lipase-catalyzed resolutions to which the low-temperature method seems to be promising to enhance the enantioselectivity are also summarized. 

Similar temperature effect using other racemic alcohols such as 2-hydroxymethyl-1,4-benzodioxane (4), 2-phenylpropanol (5), and 1-cyclohexylethanol (6) was also observed as shown in Fig. 8, obeying Equation 7. These results suggest that the temperature effect is widely applicable regardless of primary or secondary alcohols and an origin of lipase. 

The lipase-catalyzed DKRs provide only (/ )-products to obtain (5 )-products, we needed a complementary (5 )-stereoselective enzyme. A survey of (5 )-selective enzymes compatible to use in DKR at room temperature revealed that subtilisin is a worthy candidate, but its commercial form was not applicable to DKR due to its low enzyme activity and instability. However, we succeeded in enhancing its activity by treating it with a surfactant before use. At room temperature DKR with subtilisin and ruthenium catalyst 5, trifluoroethyl butanoate was employed as an acylating agent and the (5 )-products were obtained in good yields and high optical purities (Table 3)P... 

Another approach to the synthesis of chiral non-racemic hydroxyalkyl sulfones used enzyme-catalysed kinetic resolution of racemic substrates. In the first attempt. Porcine pancreas lipase was applied to acylate racemic (3, y and 8-hydroxyalkyl sulfones using trichloroethyl butyrate. Although both enantiomers of the products could be obtained, their enantiomeric excesses were only low to moderate. Recently, we have found that a stereoselective acetylation of racemic p-hydroxyalkyl sulfones can be successfully carried out using several lipases, among which CAL-B and lipase PS (AMANO) proved most efficient. Moreover, application of a dynamic kinetic resolution procedure, in which lipase-promoted kinetic resolution was combined with a concomitant ruthenium-catalysed racem-ization of the substrates, gave the corresponding p-acetoxyalkyl sulfones 8 in yields... 

Finally, prochiral bis(hydroxymethyl)phenylphosphine oxide 82 was desym-metrisized using either a lipase-catalysed acetylation (Method A) or hydrolysis of the corresponding diacetyl derivative 83 (Method B), to give the chiral monoacetate 84. Application of the two reverse procedures made it possible to obtain both enantiomerically enriched forms of 84 (Equation 40). ... 

In polyester synthesis via ring-opening polymerizations, metal catalysts are often used. For medical applications of polyesters, however, there has been concern about harmful effects of the metallic residues. Enzymatic synthesis of a metal-free polyester was demonstrated by the polymerization of l,4-dioxan-2-one using Candida antarctica lipase (lipase CA). Under appropriate reaction conditions, the high molecular weight polymer (molecular weight = 4.1 x 10" ) was obtained. 

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