Lipase hydrolyzes

Triglyceride Lingual lipase Hydrolyze triglycerides into monoglycerides and free fatty acids Salivary glands Mouth stomach... 

Lipoprotein (LPLase) is required for the metabolism of both chylomicrons and VLDL. This enzyme is induced by insulin and transported to the luminal surface of capillary endothelium where it is in direct contact with the blood. Lipoprotein lipase hydrolyzes the fiitty adds from triglycerides carried by ch)4oinicrons and VLDL and is activated by apoC-II. 

Saliva. The salivary glands produce a slightly alkaline secretion which—in addition to water and salts—contains glycoproteins (mucins) as lubricants, antibodies, and enzymes. a-Amylase attacks polysaccharides, and a lipase hydrolyzes a small proportion of the neutral fats. a-Amylase and lysozyme, a mu-rein-cleaving enzyme (see p. 40), probably serve to regulate the oral bacterial flora rather than for digestion (see p. 340). 

Degreasing with lipases is beginning to be ttsed as an alternative to tensides and solvents. Lipases hydrolyze not just the fat on the outside of the hides and skins, but also the fat inside the skin structrrre. The advantage of using lipases is that they do not interfere with the structrrre other than by hydrolyzing the fat. The hpase-based process is also more environmentally acceptable than solvent- or terrside-based processes. 

As hormone-sensitive lipase hydrolyzes triacylglyc-erol in adipocytes, the fatty acids thus released (free fatty acids, FFA) pass from the adipocyte into the blood, where they bind to the blood protein serum albumin. This protein (Mv 66,000), which makes up about half of the total serum protein, noncovalently binds as many as 10 fatty acids per protein monomer. Bound to this soluble protein, the otherwise insoluble fatty acids are carried to tissues such as skeletal muscle, heart, and renal cortex. In these target tissues, fatty acids dissociate from albumin and are moved by plasma membrane transporters into cells to serve as fuel. 

Correct answer = A. Pancreatic lipase hydrolyzes dietary triacylglycerol primarily to 2-monoacylglycerol plus two fatty acids. These products of hydrolysis can be absorbed by the intestinal mucosal cells. Bile salts do not inhibit release of fatty acids from triacylglycerol, but rather are necessary for the proper solubilization and hydrolysis of dietary triacylglycerol in the small intestine. Short- and medium-chain length fatty acids enter the portal circulation after absorption from the small intestine. Synthesis of apolipoproteins, especially apo B-48, is essential for the assembly and secretion of chylomicrons. 

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. 

VLDLs are synthesized in the liver and transport triacylglycerols, cholesterol and phospholipids to other tissues, where lipoprotein lipase hydrolyzes the triacylglycerols and releases the fatty acids for uptake. The VLDL remnants are transformed first to IDLs and then to LDLs as all of their apoproteins other than apoB-100 are removed and their cholesterol esterified. The LDLs bind to the LDL receptor protein on the surface of target cells and are internalized by receptor-mediated endocytosis. The cholesterol, which is released from the lipoproteins by the action of lysosomal lipases, is either incorporated into the cell membrane or re-esterified for storage. High levels of intracellular cholesterol decrease the synthesis of the LDL receptor, reducing the rate of uptake of cholesterol, and inhibit HMG CoA reductase, preventing the cellular synthesis of cholesterol. 

Hydrolases carry out important degradative reactions in the body. During digestion, lipases hydrolyze lipids and proteases convert protein to amino acids. Hydrolases cleave large molecules into fragments used for synthesis, the excretion of waste materials, or as sources of carbon for the production of energy. In these reactions, many biopolymers are converted to monomers. Some hydrolases release energy as they act. 

In contrast to the case of HMPC, most lipases hydrolyze the racemic acetate of CPBA 9 to give a mixture of the insecticidally active (S)-CPBA 2 and the (R)-acetate 1J). Thus, the desired (S)-CPBA J2 could be separated from the (R)-acetate 10 by means of a continuous counter-current extraction using n-heptane solvent at 80°C. However, it is important to utilize the recovered (R)-acetate W for an efficient process. Fortunately, since the proton of the asymmetric carbon of the cyanohydrin acetate is labile, the antipodal (R)-acetate is easily racemized by treatment with weak organic base such as triethylamine without any side reactions. The racemized acetate J9 thus obtained was recycled as shown in Figure 6. Therefore, all of the racemic acetate 9 was converted to the desired (S)-CPBA 2 in this recycling process. The (S)-CPBA 2 obtained was esterified with (S)-2-(4-chlorophenyl)-3-methylbutyryl chloride to produce the most insecticidally active stereoisomer V2 of fenvalerate, namely esfenvalerate. The relative biocidal activities between... 

Lipase hydrolyzes the fat w hich would interfere with egg white whipping. 

Lipases can be divided into two groups according to their positional specificity. Some lipases hydrolyze only the ester bonds in positions I and 3 of glycerol, i.e., the primary esters. This is true for pancreatic lipase (Table II). Other lipases, such as many microbial lipases, hydrolyze all three ester bonds. In this case, the primary esters are probably hydrolyzed faster than the secondary ester. 

Fig. 8. Role of lipophorin in DG delivery to flight muscle. Adipokinetic hormone (AKH) is released from the corpus cardiacum and binds to the fat body, where it cause production of cAMP and entry of Ca . These second messengers activate lipolysis of triacylglycerol (TG) and production of diacylglycerol (DG). The DG leaves the fat body with the assistance of a lipid transfer particle (LTP) and is taken up by HDLp. The capacity of HDLp to carry DG is increased by binding of apoLp-HI to the surface. Ultimately, LDLp is formed and moves to the flight muscle, where a lipoprotein lipase hydrolyzes the DG to produce fatty acid (FA) and regenerate HDLp and apoLp-IIl. The FA enters the flight muscle, where it is oxidized to produce the ATP required to power flight. HDLp and apoLp-HI circulate back to the fat body to complete the cycle.

One of the largest uses for lipases174 may be in the hydrolysis and transesterification of oils and fats.175 The reactions with enzymes are much gentler than the ones used today, such as hydrolysis of a fat or oil in water at 150 260 C for 3-24 h. They are also less capital-intensive. Lipases can be used for the hydrolysis and subsequent reesterification with butyl alcohol of olive and rapeseed oils in 100% conversion. An Aspergillus lipase hydrolyzed various fats and oils in the presence of an aqueous buffer in 90-99% yields in 2-24 h.176 Much of the lipase remained in the emulsion at... 

Fig. 2. Interaction of bile acids with triacylglycerols. Lipid-soluble nutrients may be present in the triacylglycerol droplet. Lipases hydrolyze the triacylglycerols to liberate fatty acids and monoacylglycerols.

Lipase hydrolyzes the ester bond between the fatty acid residues and the glycerol backbone of triglycerides. Complete hydrolysis is neither necessary nor generally achieved prior to absorption from the intestine. Instead, the enzyme mainly produces a mixture of free fatty acids and mono- and diacylglycerides. Since all these components are amphipathic, they remain associated with the micelles. 

Lipases hydrolyze triglycerides giving rise to free fatty acids and glycerol. Assays for lipase activity include a wide range of techniques spectrophotometry,... 

Jaeger K-E, Steinbtichel A, Jendrossek D (1995) Subtrate specificities of bacterial polyhydroxy-alkanoate depolymerases and lipases bacterial lipases hydrolyze poly(tt)-hydroxyalkanoates). Appl Environ Microbiol 61 3113-3118... 

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