Lipase reaction

Singapore) was obtained for estimates Vmax and Km of free lipase reaction and and K p and for immobilised lipase reaction. Hanes-Woolf and Simplex methods were used for the evaluation of kinetic parameters owing to their strength in error handling when experimental data are subject to random errors.5... 

Koseki M, Tsuji K, Nakagawa Y, Kawamura M, Ichikawa T, Kazama M, Kitabatake N and Doi E. 1989. Effects of gum Arabic and pectin on die emulsification, the lipase reaction and die plasma cholesterol... 

Figure 3. Effect of the particle size of PEA powders on the hydrolysis by R. delemar lipase. Reaction mixtures were incubated at 30 °C. Particle size -0-, 0-0.25 mm 0-1.00 mm,...

Those lipase reactions can be the result of unspecific or specific stimuli or can even form a constitutive part in the signal transduction cascade of receptors. 

Conceptually, assays for lipase activity using the colorimetric method (copper-soap procedure Basic Protocol 2) are similar to titrimetry in that liberated fatty acids are being measured however, the colorimetric method is more specific for fatty acids (Lowry and Tinsley, 1976). Quenched subsamples of emulsified acylglycerol/lipase reaction mixtures are combined with the biphasic mixture of cupric acetate/pyridine and benzene. Cupric salts of the fatty acids are formed (molar stoichiometry of fatty acid to Cu2+ of 4 2) and these soaps, which are blue in color, are partitioned into benzene to allow for quantification by measuring absorbance of the clear benzene phase at 715 nm. 

When identical lipase reaction subsamples are measured for fatty acid levels by both titrimetry (Basic Protocol 1) and colorimetry (Basic Protocol 2), estimates by the colorimetric procedure are only 60% of those obtained by titrimetry. However, the nature of this rela-... 

Analysis of three lipase reactions using the titrimetric method illustrates typical reaction progress curves and how, as well as the need, to estimate initial rates by tangential analysis (Fig. C3.1.1). The corresponding initial reaction velocities were 27.5 U/mg forBurkholderia cepacia (formerly, Pseudomonas cepacia) li-... 

Aside from the time required to prepare reagents, the least amount of time is required per lipase assay by the spectrophotometric method, and the greatest amount of time is required per assay for the titrimetric method. Although all assays are described as requiring up to 30 min for the reaction mixture to be subsampled, time savings can be realized by subsampling more frequently over a shorter period of time, as long as one obtains valid initial rate data. Thus, for all assays, the time involved to run the lipase reaction can be normalized to be the same at -10 to 15 min. The difference in time requirements for the protocols becomes embedded in sample workup procedures. 

Lipase Reactions to Intermediates for Cardiovascular Therapy (R)-Glycidyl butyrate an intermediate to / -blockers... 

The meso-diol was enzymatically acetylated, which afforded the mono-acetate with 25,6/ - configuration. Hydrolysis by lipase reaction (PLE) gave an intermediate through which four reaction steps resulted in the N-protected (Cbz-group) ethyl ester, which could be finally transformed to the (—)-enantiomer of the target alkaloid (—) -gephyrotoxin. 

Fig. 3. Effect of acid chain length on ester synthesis catalyzed by POS-PVA lipase Reactions were carried out at 37°C for 24 h using n-butanol. C4, Butyric acid C8, caprylic acid 02, lauric acid 06, palmitic acid.

Index Entries Alcoholysis vegetable oils lipases reaction kinetics biodiesel. 

In addition, FAStEs in VODDSEC can be purified easily by adopting lipase reaction. C. rugosa lipase strongly hydrolyzed TAGs, but weakly hydrolyzed FAStEs. ffence, VODDSEC was hydrolyzed using this lipase. After the reaction, the oil layer was subjected to short-path distillation, and the FAStE fraction was recovered. FAStEs were purified to 97% (yield, 88%) (Hirota et al., 2003). 

Free sterols were purified from the reaction mixture, which mainly contained sterols and FAMEs, by n-hexane fractionation because the sterols were poorly soluble in n-hexane but FAMEs and FFAs were readily soluble in the organic solvent. The process comprising lipase reaction and n-hexane fractionation purified sterols with 87% recovery of the initial content in OAStEs (purity of sterols, 99%) (Shimada et al., 2003a). 

Some element reactions for BDF production can be applied widely to oil and fat processing. Since enzyme-catalyzed reactions proceed efficiently under mild conditions, they are suitable for the treatment of materials including unstable compounds. Furthermore, enzymes can convert only a desired compound to its other molecular form because of the strict substrate specificity compared with chemical catalysts. We hope that much attention will be focused on the superiority of enzyme, and that lipase reactions will be applied more and more as the practical process in the oil and fat industry. 

Shimada, Y. 2001c. Application of lipase reactions to separate and purification of useful materials. INFORM, 12,1168-1174. 

Shimada, Y. 2003c. Lipase reactions applicable to purification of oil- and fat-related materials. In Akoh, C. C. and Lai, O.-M. (Eds.), Healthful Lipids (pp. 395 10). Champaign, IL AOCS Press. 

There is considerable worldwide interest in the application of lipases for fat modification and ester synthesis. In systems with low water activity, lipases are able to catalyze ester synthesis as well as interesterification reactions in fats. The lipase reactions under low water activity can be performed in several ways. We consider batch or continuous reactions in melted fats by use of immobilized lipases as the most relevant way for the industry. 

Enantioselective Hydrolysis with Arthrobacter Lipase. Reaction performance with the Arthrobacter lipase was studied in detail. The pH profile curve of the zero-order reaction exhibited a pH-optimum around 7.0, and spontaneous hydrolysis was not significant at pH... 

Gitsov et al 10) produced a nanoreactor fi om laccase and linear poly(ethylene oxide)-dendritic poly(benzyl ether) diblock copolymers. A notable feature of this system is the presence of hydrophobic dendritic pockets that increase the local concentration of water-insoluble organic compounds near the active site where they are oxidized. Li and Hsieh (77) employed a hydrogel fiber membrane, with a large surface area and improved organic solvent solubility in order to facilitate lipase reactions. He (72) grafted lipase onto silica particles, which permitted him to carry out synthesis of polyesters, polycarbonates, polyphosphates, and their copolymers at temperatures up to 150°C. 

To facilitate lipase-reactions in supercritical CO2, Bruns et al (32) impregnated a lipase within amphiphilic co-networks that comprised a fluorophilic phase. This resulted in substantially higher enzyme activity relative to the enzyme powder. It may be noted that the bio-artificial materials reported by Silvestri et al (7) can also be considered a form of enzyme immobilization. 

Rates of lipase reaction can therefore be measured by determining either (a) the rate of disappearance of the substrate, the triglyceride, or (b) the rate of production of the fatty acids. Determination of the rate of diglyceride, monoglyceride, or glycerol produetion is theoretically possible, but is practically difficult and seldom carried out. 

Proteins, naturally occurring macromolecular surfactants with amphiphilic nature, are adsorbed onto interfaces, thereby affecting the physical states of interfaces. Many enzymes are involved in catalytic reaction at interfaces. For enzymatic reaction at interfaces, different from the reaction in homogeneous systems, interfacial contact and subsequent conformational change of enzymes are important events determining their catalytic activity. In this chapter, I will describe the conformation of proteins and their interaction (protein-protein and protein-surfactant) at interfaces (mainly liquid-liquid interfaces). The characteristics of enzymatic reaction at liquid-liquid and solid-liquid interfaces, especially lipase reaction, wiU also be described. 

Tris buffer pH 8 was used in the esterase reactions and phosphate buffer pH 7 was used in the lipase reactions. 5% DMSO or MeOH was aiso used in all the reactions to increase the solubility of 4 in aqueous buffer. The substrate concentration was 2.2 mM. Cat., catalyst. 

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