Carrier of activity

Acyl-coenzyme A compounds, which, because of their high acetyl group transfer potential represent carriers of activated acyl groups in biological systems, are prepared from the corresponding carboxylic acid, CDI, and coenzyme a.[4h5],[177],[182],[183]... 

The reaction involves biotin as a carrier of activated HCO3 (Fig. 14-18). The reaction mechanism is shown in Figure 16-16. Pyruvate carboxylase is the first regulatory enzyme in the gluconeogenic pathway, requiring acetyl-CoA as a positive effector. (Acetyl-CoA is produced by fatty acid oxidation (Chapter 17), and its accumulation signals the availability of fatty acids as fuel.) As we shall see in Chapter 16 (see Fig. 16-15), the pyruvate carboxylase reaction can replenish intermediates in another central metabolic pathway, the citric acid cycle. 

A second report of organic carbonate production from epoxide and C02 utilizes copper(I) cyanoacetate, Cu(02CCH2CN), as a carrier of activated C02 (158). Reaction of propylene oxide with Cu(02CCH2CN) at 130°C for 10 hours yields propylene carbonate in 83% yield, based on the... 

Histidine is converted into 4-imidazolone 5-propionate (Figure 23.24). The amide bond in the ring of this intermediate is hydrolyzed to the TV-formimino derivative of glutamate, which is then converted into glutamate by transfer of its formimino group to tetrahydrofolate, a carrier of activated one-carbon units (Section 24.2.6). 

Tetrahydrofolate, a carrier of activated one-carbon units, plays an important role in the metabolism of amino acids and nucleotides. This coenzyme carries one-carbon units at three oxidation states, which are interconvertible most reduced—methyl intermediate—methylene and most oxidized—formyl, formimino, and methenyl. The major donor of activated methyl groups is -adenosylmethionine, which is synthesized by the transfer of an adenosyl group from ATP to the sulfur atom of methionine. -Adenosylhomocysteine is formed when the activated methyl group is transferred to an acceptor. It is hydrolyzed to adenosine and homocysteine, the latter of which is then methylated to methionine to complete the activated methyl cycle. 

Liposomes have been used for years as components of drug delivery systems, and as transdermal carriers of active ingredients in the cosmetic industry (307, 308). More recently, liposomes have found use in the food and nutritional supplement industries. Keller (308) lists more than a dozen nutritional products on the market that have been formulated with novel liposome-based delivery systems. In the food area, hposomes have been studied for their ability to encapsulate and provide controlled release of enzymes (309, 310), and liposome-encapsulated enzymes have been used to accelerate the ripening of cheese (311). 

Tetrahydrofolate (THF) is the major source of 1-carbon units used in the biosynthesis of many important biological molecules. This cofactor is derived from the vitamin folic acid and is a carrier of activated 1-carbon units at various oxidation levels (methyl, methylene, formyl, formimino, and methenyl). These compounds can be interconverted as required by the cellular process. The major donor of the 1-carbon unit is serine in the foUowing reaction ... 

S-Adenosyl methionine An important carrier of activated methyl groups. It is formed by the condensation of ATP with the amino acid methionine catalyzed by the enzyme methionine adenosyltransferase in a reaction that releases triphosphate. 

The experiential dimension does not have to stay in the fragrance or color arena. It is expanding to the beads, pearls, and other attractive elements seen in personal care products. A recent example is the Rainett aux Algues Marines LDLD introduced in France by Werner Mertz. This product contains natural marine algae extracts encapsulated in beads. The extracts offer hand care benefits. Pearls or beads can be used as carriers of actives to enhance efficacy or mildness perceptions. 

In the "ideal" nuclear reactor all fission products and actinides produced are contained in the fuel elements. In all practical reactors there are four processes through which radioactivity leaves the reactor vessel in all cases the carrier of activity is the coolant ... 

Edible coatings cannot be typically considered packages bnt rather physical food protecting barriers, which can additionally act as carriers of active and/or bioactive substances and controlled release of flavor molecules, giving them an added-valne. Edible film can carry active components, snch as flavors and other food additives, in the form of hard capsules, soft gel capsules, microcapsules, soluble strips, flexible pouches, coatings on hard particles, and others. ... 

In the last decade, significant number of the works devoted to the quantitative description of processes of release of low molecular weight medicinal substances from polymeric matrixes. One of the major problems of modem medicine is creation of new methods of the treatment based on purposeful local introduction of medical products in a certain place with set speed. The basic requirement shown to the carrier of active material, its destraction and a gradual conclusion fiom an organism [1,2]. 

This review focuses on the use of hydrogen peroxide as the terminal oxidant. The virtues of hydrogen peroxide as a readily available and green carrier of active oxygen have been praised numerous times [4—6]. In the current context, it is particularly gratifying that hydrogen peroxide is activated toward electrophilic oxidations by... 

Pyruvate carboxylase is a mitochondrial enzyme which requires Mg and biotin as a carrier of activated carbon dioxide. In addition, it has an absolute requirement for acetyl-CoA, which acts as an allosteric activator (page 340). In this way the accumulation of acetyl-CoA normally triggers the formation of oxaloacetate. If ATP is in short supply, oxaloacetate will combine with some of the acetyl-CoA to form citrate, and so be drawn into the citrate cycle. On the other hand, if there is a surplus of ATP, both this and the oxaloacetate will be used for gluconeogenesis. 

Using Ru catalyst can increase the productivity of the device and decrease the energy consumption by 1.2GJ t h The life period, poison and anti-poisoning of Ru catalyst is the same as Fe catalyst, and its life period is dependent on the loss of the carrier of activated carbon. ... 

In the oxidative decarboxylation of pyruvate and oxoglutarate, as shown in Figure 3, TPP functions as a carrier of active aldehyde to form the intermediates, hydroxyethyl-TPP and a-hydroxy-P-carboxypropyl-TPP, which are finally transferred to coenzyme A (CoA) to form acetyl-CoA and succinyl-CoA, respectively. 

Uridine diphosphate is the carrier of active glucose. Uridine triphosphate, entirely analogous to ATP, can exchange the third phosphate group for a sugar molecule and hold it in an energy-rich bond ... 

Tsuda, T Chujo, Y Saegusa, T. CopperfI) Cyanoacetate as a Carrier of Activated Carbon Dioxide. J. Chem. Soc. Chem. Commun. 1976, 415 16. 

In pharmaceutical sciences, colloids are used as carriers of active substances in order to (a) improve the bioavailabiUty of poorly water-soluble drugs (Schmidt Boodmeier, 1999),... 

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