Lipase activity control

Superko, H., Bortz, W., Williams, P., Albers, J. and Wood, P., Caffeinated and decaffeinated coffee effects on plasma lipoprotein cholestrol, apolipoprotiens and lipase activity A controlled, randomized trial. American Journal of Clinical Nutrition 54, 599-605, 1991. 

One of the most promising applications of enzyme-immobilized mesoporous materials is as microscopic reactors. Galameau et al. investigated the effect of mesoporous silica structures and their surface natures on the activity of immobilized lipases [199]. Too hydrophilic (pure silica) or too hydrophobic (butyl-grafted silica) supports are not appropriate for the development of high activity for lipases. An adequate hydrophobic/hydrophilic balance of the support, such as a supported-micelle, provides the best route to enhance lipase activity. They also encapsulated the lipases in sponge mesoporous silicates, a new procedure based on the addition of a mixture of lecithin and amines to a sol-gel synthesis to provide pore-size control. 

A second route (route B in Fig. 1) relies on an initiation process with an (meth)acryl hydroxyl compound and is adopted from the chemical ROP of lactones. The controlled character of these polymerizations ensures a virtually quantitative initiation and thus incorporation of hydroxy-functional initiator (e.g., acrylate) into the polymer chain. However, this is not automatically the case for lipase-catalyzed ROP due to the different mechanism. The latter follows an activated monomer mechanism in which the lipase activates any carbonyl group of a carboxylic acid derivative present in the system. It has recently been shown that acrylation using hydroxy-functional acrylate initiators like hydroxy ethyl(meth)acrylate (HEMA or... 

Regulation The concentration of free fatty acids in the blood is controlled by the rate at which hormone-sensitive triacylglycerol lipase hydrolyzes the triacylglycerols stored in adipose tissue. Glucagon, epinephrine and norepinephrine cause an increase in the intracellular level of cAMP which allosterically activates cAMP-dependent protein kinase. The kinase in turn phosphorylates hormone-sensitive lipase, activating it, and leading to the release of fatty acids into the blood. Insulin has the opposite effect it decreases the level of cAMP which leads to the dephosphorylation and inactivation of hormone-sensitive lipase. 

The dynamic cyanohydrin system was next challenged with lipase-catalyzed transesterification resolution using different operational conditions. Thus, different lipases, organic solvents, additives, and acyl donors were evaluated. Isopropenyl acetate 26 was chosen and used as acyl donor because its reaction produces acetone as by-product, which does not interfere in the reaction and the NMR spectra. Molecular sieve 4 A was also added in the dynamic resolution process to control the water activity. The lipase preparation PS-C I was chosen in the resolution process since it expressed the highest lipase activities for both the substrate structure and the enantiomeric selectivities. Different organic solvents were also... 

The oxygen level in the milkfat may be limited by either active or passive actions. For passive control, processing procedures and plant design are established to minimize air exposure. Deaeration devices (74), vacreation (60), the use of antioxidants (72), effective destmction of lipases (75), and nitrogen spanning of container headspace are examples of active control of product quality. 

The rate of triglyceride output from the plasma is mainly controlled by the lipoprotein lipase activity of peripheral tissues. Post-heparin plasma lipolytic activity in vitamin-C-deficient guinea pigs decreases considerably. In addition, in some of the animals the response of the plasma lipolytic activity to intravenously administered heparin is also prolonged (45). Similar results have been reported in vitamin-C-deficient baboons (46). 

Colombie, S., Tweedell, R. J., Condoret, J. S., and Marty, A., Water activity control a way to improve the efficiency of continuous lipase esterification, Biotechnol. Bioeng., 60, 362-368, 1998. 

The aqueous extract of Platycodi radix inhibited the pancreatic lipase activity in a dose-dependent manner in the assay system using triolein emulsified with phosphatidylcholine, Fig. (6). At 2, 3 and 4 h after the administration of the aqueous extract of Platycodi radix, the plasma triacylglycerol concentration was significantly lower in the treated rats than in the control group, Fig. (7). 

Fig. (14) Effects of chondroitin sulfate on pancreatic lipase activity. Results are expressed as means s.e.m. of four experiments. p<0.05, significantly different from control.

Figure 18.11 Control of triacylglycerol lipase activity in adipose cells by a cyclic AMP-mediated cascade system. 

FIGURE 15.1 Effect of non-shaved kombu (NSK) and tororokombu (TK) on pancreatic lipase activity in vitro. Pancreatic lipase (from porcine) activity was measured using a Lipase Kit S according to the manufacturer s protocoL Data are presented as the mean SE (n = 5). p < 0.05, p < 0.005 versus control p < 0.05 NSK versus TK. 

Rodrigues, B., Braun, J.E., Spooner, M. Severson, D.L. (1992) Can-J-Physiol-PhamuKol, 70, 1271-1279. Regulation of lipoprotein lipase activity in cardiac myocytes from control and diabetic rat hearts by plasma lipids. 

The vast majority of methods described for estimating lipase activity are based on the determination of liberated fatly acids. In a typical method the substrate, emulsified with gelatin or gum arabic, is mixed with buffer (ammonia-ammonium chloride buffer, pH 9.0, is often employed) and Ca++. The lipase is added and the mixture incubated for a definite period. The whole contents are then titrated witb alkali and compared with a control without lipase. Alternatively, samples may be removed at definite intervals for titration. Several methods of this type have been described (204-208). Very long periods of incubation, e.g. 6-7 days, with samples taken for titration every 24 hotus have... 

Two lipases, i.e. LPL and H-TGL, in this postheparin plasma were separately measured using the antiserum prepared against H-TGL(3). Plasma samples from 12 age-matched control subjects were used for the lipoprotein analysis. Normal values of postheparin plasma lipase activities were those for 13 normo-lipidemic male subjects reported elesewhere(3). The serum concentration of apolipoprotein A-I, A-IE and apolipoprotein B were measured by a immunodiffusion technique using specific anti-serum. 

---