Nonspecific lipase,

A number of specific lipases are used for ester synthesis (eq. 4) transesterification, eg, acidolysis with 1,3 specific lipase (eq. 5) and hydrolysis reactions, eg, with nonspecific lipase (eq. 6). 

The experimental results for Lipozyme IM, which exhibits specificity in the 1,3 positions, and Novozym 435, a nonspecific lipase, are presented... 

A New Immobilized Positional Nonspecific Lipase for Fat Modification and Ester Synthesis... 

HELDT-HANSEN ET AL. Immobilized Positional Nonspecific Lipase... 

In the interesterification of fats, 1,3-positional specific lipases catalyze reactions in which only the fatty acids in the a-positions of the triglycerides take part, whereas positional nonspecific lipases are able to catalyze reactions in which the fatty acids from both the a- and / -positions take part. In transesterification between two types of fat, the positional non-specific lipase is therefore able to randomize the fatty acids, resulting in the same fatty acid composition in the triglycerides as obtained in the commercially important chemical randomization process. In ester synthesis, positional non-specific lipases catalyze the reaction with both primary and secondary alcohols whereas positional specific lipases are more or less specific for primary alcohols. 

Lipase. Interesterification of triacylglycerols in the presence of a regiospecific lipase or a nonspecific lipase and free fatty acids can be used to modify the physical or nutritional characteristics of fats. Lipases from Aspergillus sp. (47,48) and Rhizopus... 

The possible application of enzyme-assisted reactions for production of lower value nonspecialty lipids such as margarine hardstocks and cooking oils has been reported (50). When nonspecific lipases, such as those from Candida cylindraceae and C. antarctica, are used as biocatalysts for interesterification of oil blends, the TAG... 

Stmctured lipids containing both GLA and n-3 PUEAs may be of interest because of their desired health benefits. Performing an acidolysis between y-linolenic acid (18 3n-6 GLA) rich oils, such as those from borage and evening primrose, and free EPA and DHA, Senanayake and Shahidi (36) used the nonspecific lipase PS-30... 

Pancreatic carboxylester lipase, secreted by the pancreas as an active enzyme without proteolytic activation, displays broad substrate specificity and has therefore received many names in the literature carboxylesterase, bile salt-stimulated (or activated or dependent) lipase (due to its absolute requirement for bile salts to hydrolyze insoluble substrates), carboxylester lipase or hydrolase, cholesterol esterase, lysophospholipase, nonspecific lipase, and monoglyceride lipase. The IUPAC classification of the enzyme has been either EC.3.1.1.1 (carboxylester hydrolase) or EC.3.1.1.13 (cholesterolester hydrolase) (Table 2). 

The bile-salt-dependent lipase of pancreatic juice has many names such as cholesterol esterase, nonspecific lipase, the most rational being carboxyl ester lipase [27], In the case of water-insoluble substrates this enzyme has an absolute requirement for bile salts specifically having hydroxyl groups in the 3a and la positions [28.29]. The best documented role for this enzyme is to allow the absorption of dietary cholesterol, through hydrolysis of cholesterol esters in the lumen. The enzyme also catalyzes the esterification of cholesterol and a role for it has been proposed in cholesterol absorption [30]. In addition, a wide range of primary and secondary fatty acyl esters including glycerides, vitamin A and E esters are hydrolyzed by this enzyme. 

In our study, we conducted the enzyme-catalyzed methanolysis of rapeseed oil using Novozym 435, a well-known nonspecific lipase. Novozym 435 facilitates reactions between a wide variety of alcohols and is also a remarkably heat-tolerant enzyme [6, 8], Watanabe et al. [9] previously reported that immobilized Candida antarctica lipase was inactivated in the presence of more than half the stoichiometric amount of methanol against total fatty acids in the oil. This disadvantage was surmounted by the utilization of three-step methanolysis, in which only one third of the total amount of methanol was added in each stage [7, 9]. 

The Novozym 435 (Lipase B from C. antarctica, EC 3.1.1.3, a nonspecific lipase immobilized on macroporous acrylic resin, 1-2% water content, 10,000 propyl laurate... 

Again, the use of lipase catalyst for interesterification of edible fats and oils has advantages over the classical chemical catalysts. One of the most attractive features is the unique specificities possible with their use. Nonspecific lipases provide reactions like the random chemical catalyzed interesterification. Specific lipases make it possible to produce fats and oils with a customized triglyceride structure. The enzymatic process can be selective with the use of a positional specificity lipase. These processes are usually much slower and more sensitive to the reaction conditions to provide a better control over the reaction results. Also, the lipases can operate under milder reaction conditions, temperature and pressure, that minimize the formation of side products. 

In a series of two articles, the composition of palm olein and the transesterification of palm olein by nonspecific lipases were determined chromatographically using a Cjg column (RI detector) and a 63.5/36.5 acetone/acetonitrile mobile phase [863, 864]. The generation of a profile of end products was complete in 40 min. It is interesting to note that the retention time for the palm olein varied at least 1.5 min from injection to injection (29-30.5 min). No comment was made as to the source of this variability. Nevertheless, the profiles were consistent and 11 transesterification products were separated from the original components and quantitated. 

The substrate specificity of enzymes shows the following differences. The occurrence of a distinct functional group in the substrate is the only prerequisite for a few enzymes, such as some hydrolases. This is exenqtlified by nonspecific lipases (cf. Table 3.21) or peptidases (cf. 1.4.5.2.1) which generally act on an ester or peptide covalent bond. 

The stereospecific distribution of fatty acids in TAG molecules of DHA, EPA and EPA+DHA-enriched structured lipids synthesized in our laboratory was determined. Tables V and VI report the positional distribution of fatty acids in structured lipids examined. The results of this study showed that DHA was randomly distributed over all three positions (34.6% at snA 33.5% at sn-2 and 35.9% at snA>) of the TAG molecules of DHA-enriched borage oil (Table V). In DHA-enriched evening primrose oil, however, this fatty acid was mainly occupied by the sn 2 position (38.2%), followed by snA (33.1%) and sn- (24.5%) positions (Table VI). It should be noted that these DHA-enriched structured lipids were prepared using Novozym-435 from Candida antarctica as the biocatalyst. The positional specificity of Novozym-435 depends on the type of substrates used in various reactions. In some reaction systems, this enzyme behaves as a nonspecific lipase whereas in other systems it exhibits 5W-1,3 regiospecificity (77). Based on the reaction conditions enq)loyed in this study, Novozym-435 functions as a nonspecific lipase. 

Lipases from different sources have shown different substrate specificity and catalytic activity. Lipases with narrow specificity are not suitable for biodiesel production. The performance of regiospecific lipases can possibly improve when used with nonspecific lipases in combination. Also, some lipases show more hydrolytic activity while others... 

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