Lipolytic

There is quite a large body of literature on films of biological substances and related model compounds, much of it made possible by the sophisticated microscopic techniques discussed in Section IV-3E. There is considerable interest in biomembranes and how they can be modeled by lipid monolayers [35]. In this section we briefly discuss lipid monolayers, lipolytic enzyme reactions, and model systems for studies of biological recognition. The related subjects of membranes and vesicles are covered in the following section. 

Manufacture of Fatty Acids and Derivatives. Splitting of fats to produce fatty acids and glycerol (a valuable coproduct) has been practiced since before the 1890s. In early processes, concentrated alkaU reacted with fats to produce soaps followed by acidulation to produce the fatty acids. Acid-catalyzed hydrolysis, mostly with sulfuric and sulfonic acids, was also practiced. Pressurized equipment was introduced to accelerate the rate of the process, and finally continuous processes were developed to maximize completeness of the reaction (105). Lipolytic enzymes maybe utilized to spHt... 

Linsensatz, m. system of lenses, lipidloslich, lipoidldsllch, a. lipide-aoluble. Lipolyse, /. lipolysis. lipolytisch, a. lipolytic. 

HM74/-A Nicotinic acid Lipid lowering, anti-lipolytic... 

Table 3.1 Lipolytic genes identified in metagenome screens.

Otfier fiormones accelerate tfie release of free fatty acids from adipose tissue and raise tfie plasma free fatty acid concentration by increasing the rate of lipolysis of the triacylglycerol stores (Figure 25—8). These include epinephrine, norepinephrine, glucagon, adrenocorticotropic hormone (ACTH), a- and P-melanocyte-stimulat-ing hormones (MSH), thyroid-stimulating hormone (TSH), growth hormone (GH), and vasopressin. Many of these activate the hormone-sensitive hpase. For an optimal effect, most of these lipolytic processes require the presence of glucocorticoids and thyroid hormones. These hormones act in a facilitatory or permissive capacity with respect to other lipolytic endocrine factors. 

Figure 25-8. Control of adipose tissue lipolysis. (TSH, thyroid-stimulating hormone FFA, free fatty acids.) Note the cascade sequence of reactions affording amplification at each step. The lipolytic stimulus is "switched off" by removal of the stimulating hormone the action of lipase phosphatase the inhibition of the lipase and adenylyl cyclase by high concentrations of FFA the inhibition of adenylyl cyclase by adenosine and the removal of cAMP by the action of phosphodiesterase. ACTFI,TSFI, and glucagon may not activate adenylyl cyclase in vivo, since the concentration of each hormone required in vitro is much higher than is found in the circulation. Positive ( ) and negative ( ) regulatory effects are represented by broken lines and substrate flow by solid lines.

Cutinase is a hydrolytic enzyme that degrades cutin, the cuticular polymer of higher plants [4], Unlike the oflier lipolytic enzymes, such lipases and esterases, cutinase does not require interfacial activation for substrate binding and activity. Cutinases have been largely exploited for esterification and transesterification in chemical synthesis [5] and have also been applied in laundry or dishwashing detergent [6]. 

In their study of untrained vs. trained swimmers, Collomp et al.40 suggested that specific training may be the catalyst that stimulates caffeine s ergogenic effects during high intensity, anaerobic activity. The results of many studies have also suggested that only well-trained athletes derive significant benefits from caffeine due to the athletes previously stimulated lipolytic activity and the increased size and density of their mito-chondria.40-52-58-59... 

Van Schaick EA, Tukker HE, Roelan HCPF, Ijzerman AP, Danhof M. Selectivity of action of 8-alkylamino analogues of /V6-cyclopentyladenosine in vivo hemodynamic versus anti-lipolytic responses in rats. Br J Pharmacol 1998 124 607-618. 

Methylpyrazine-2- Acipimox Anti-lipolytic Oxidation Pseudomonas putida Single-stage fermentation [6]... 

Fats deteriorate in two ways. One is normally a chemical process the other is normally enzymatic. They are oxidative rancidity and lipolytic rancidity. In the former, oxygen (normally in the form of a free radical) adds across double bonds. As this is a zero activation energy process it is... 

Long ago it was noticed that the baking quality of white flour improved with storage for 1-2 months. This effect occurred more rapidly if the flour was exposed to the air. During storage, initially the level of free fatty acids increases, presumably owing to lipolytic activity. Lipoxygenase activity then produces oxidised fatty acids as the proportion of linoleic and linolenic acids falls while the number of -S-S- bonds decreases. 

In any of these cases lipolytic activity can shorten the shelf life of the product or render it totally unacceptable. 

This specification is for butter oil, which is butter with the water removed. The free fatty acid limit is to detect lipolytic rancidity while peroxide value specification is to limit oxidative rancidity. The copper limit arises because copper catalyses the oxidation of fats. The absence of neutralising substances is to prevent a high titration for free fatty acids being covered up by the addition of alkali. 

Stimulation of protein synthesis in many tissues Mobilization of depot lipids from adipose tissue (lipolytic effect)... 

The effectiveness of proteolytic, amylolytic, and lipolytic detergent enzymes is based on enzymatic hydrolysis of peptide, glucosidic, or ester linkages. The mainstay of the market has been the protease types. 

Butcher RW, Ho RJ, Meng HC, Sutherland EW 1965 Adenosine S -monophosphate in biological materials. II. The measurement of adenosine S -monophosphate in tissues and the role of the cyclic nucleotide in the lipolytic response of fat to epinephrine. T Biol Chem... 

The general rules that should therefore be observed include the use of a blanket of nitrogen whenever possible and evaporation of solvents at the lowest feasible temperatures, which must not exceed 50°C. The addition of an antioxidant such as butylated hydroxytoluene (2,6-di-/-butyl-4-methylphenol) to the extraction solvents (0.1 g 1 ) might be necessary to prevent deterioration of unsaturated lipids but it is essential for storage of lipid extracts at about 0.1% of the weight of lipid. Inactivation of lipolytic enzymes may usually be achieved by addition of an alcohol such as methanol or, in some cases, isopropanol. The latter is recommended for some more stable enzymes sometimes found in plant tissues. Alternatively the plant may be briefly immersed in boiling water. 

Specihc poly anions such as dextran sulfate (DS) appear to exhibit strong anti-HIV activity in vitro [36,37]. Human oral administration of DS is poorly absorbed, but intravaneous administration does result in increased plasma lipolytic activity [38]. Poly anions that have been considered for intravaginal anti-HIV activity include DS, carrageenan, heparin, heparan sulfate, dermatan sulfate, pentosan polysulfate, fucoidan chondroitin sulfate, keratan sulfate, and PAVAS [21,22,39,40],... 

The best-known effect of APOE is the regulation of lipid metabolism (see Fig. 10.13). APOE is a constituent of TG-rich chylomicrons, VLDL particles and their remnants, and a subclass of HDL. In addition to its role in the transport of cholesterol and the metabolism of lipoprotein particles, APOE can be involved in many other physiological and pathological processes, including immunoregu-lation, nerve regeneration, activation of lipolytic enzymes (hepatic lipase, lipoprotein lipase, lecithin cholesterol acyltransferase), ligand for several cell receptors, neuronal homeostasis, and tissue repair (488,490). APOE is essential... 

Diacylglycerol is a better snbstrate than triacylglycerol for the lipolytic enzymes that are secreted by the pancreas. 

Pancreatic amylase Infants with this deficiency begin life unable to digest starch. However, after a few months, the pancreas starts to produce sufficient amylase. Adults produce such an excess of this enzyme that even patients with severe pancreatitis (who are unable to produce sufficient lipolytic or proteolytic enzymes) can produce sufficient amylase to cope with a normal amount of starch in the diet. 

Hormones can modify the concentration of precursors, particularly the lipolytic hormones (growth hormone, glucagon, adrenaline) and cortisol. The lipolytic hormones stimulate lipolysis in adipose tissue so that they increase glycerol release and the glycerol is then available for gluconeogenesis. Cortisol increases protein degradation in muscle, which increases the release of amino acids (especially glutamine and alanine) from muscle (Chapter 18). 

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