Lipoprotein lipase stability

Posner, I., Bermudez, D. 1977. Lipoprotein lipase stabilization by a factor of bovine milk. Acta Cient. Venez. 28, 277-283. 

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. 

ApoC-II is expressed in liver and intestine, and both the neural retina and RPE (Li et al., 2006). In contrast to ApoC-I, it can function as an activator of lipoprotein lipase. Similar to ApoA-I, ApoA-II, and ApoE, in the absence of lipid to stabilize its structure, ApoC-II forms amyloid assemblies. 

To increase the stability of milk products. Lipoprotein lipase is probably the most important in this regard as its activity leads to hydrolytic rancidity. It is extensively inactivated by HTST pasteurization but heating at 78°C x 10 s is required to prevent lipolysis. Plasmin activity is actually increased by HTST pasteurization due to inactivation of inhibitors of plasmin and/or of plasminogen activators. 

Each apolipoprotein has one or more distinct functions. The apoB proteins probably stabilize the lipoprotein micelles. In addition, apoB-100 is essential to recognition of LDL by its receptors. The 79-residue apoC-II has a specific function of activating the lipoprotein lipase that hydrolyses the triacylglycerols of chylomicrons and VLDL. Lack of either C-II or the lipase results in a very high level of triacylglycerols in the blood.11... 

Anderson, M. 1982b. Stability of lipoprotein lipase in bovine milk. J. Dairy Res. 49, 231-237. 

Shimada, K., Lanzillo, J.J., Douglas, W.H.J., Fanburg, B.L. 1982. Stabilization of lipoprotein lipase by endothelial cells. Biochim. Biophys. Acta 710, 117-21. 

Jackson RL, Tajima S, Yamamura T, Yokoyama S, Yamamoto A. Comparison of apolipoprotein C-II-deftcient triacylglycerol-rich lipoproteins and trioleoyiglycerol/phosphatidylcholine-stabilized particles as substrates for lipoprotein lipase. Biochim BiophysActa 1986 875 211-19. 

Based on in vitro studies, it was reported that bile salts above their critical micellar concentrahon (CMC) are required for orlislal to be able to effectively inhibit HPL [29] and lipoprotein lipase [111]. The fact that the inhibited HPL could be reactivated by reducing the bile salt concentration below its CMC suggested that bile salts (above their CMC) may stabilize the acyl-hpase complex [29]. 

With this state of uncertainty, it is not possible to define the true structural and functional role of the chylomicron protein. Chylomicrons are generally considered as a large central sphere of glycerides with small amounts of cholesterol, phospholipid, and protein loosely adsorbed on the surface, forming, according to Lindgren and Nichols (1960), small lipoprotein subunits. Aside from physical stabilization, the adsorbed components at the surface appear to impart biochemical specificity to the chylomicron particles, as indicated by Korn s studies (1955) showing that chylomicrons, and not simple fat emulsions, form an optimal substrate for the enzyme lipoprotein lipase. 

The metabolism of lipid emulsions has long been considered to be similar to that of chylomicrons with intravascular lipolysis by lipoprotein lipase (LPL) being followed by tissue uptake of remnant particles. However, other studies have suggested that lipid emulsions are cleared from blood with less lipolysis than chylomicrons and that a substantial number of emulsions can be cleared as almost intact whole particles by different tissues. The metabolism of lipid emulsions is affected by many factors, including triglyceride (TG) composition. For example, MCT LCT emulsions are cleared faster from blood than pure LCT emulsions. Recently, it was reported that pure FO emulsion particles are removed from blood faster and by different pathways as compared with LCT emulsions. Removal of LCT emulsions is modulated by LPL, apolipoprotein E (apoE), LDL receptor (LDL-R), and lactoferrin-sensitive pathways. In contrast, clearance of FO emulsions relies on LPL to a much lesser extent and is apparently independent of apoE, LDL-R, and lactoferrin-sensitive pathways. It can therefore be noted that the materials selecteds to develop a nanoemulsion composition may not only affect the physicochemical properties and stability of the formulation but may alter significantly the biofate and efficacy of the nanoemulsions. 

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