1.2- DAG

O Keefe A and Deacon DAG 1988 Cavity ring-down optical spectrometer for absorption-measurements using pulsed laser sources Rev. Sol. Instrum. 59 2544-51... 

Two ET GPCR subtypes, ET and ETg, have been cloned from human tissues. Both leceptois utilize IP /DAG for transduction. ET-1 and ET-2 have similai affinities for the ET subtype, whereas the affinity of ET-3 is much lower. All three peptides have similat affinities for the ETg subtype. Both receptor subtypes ate widely distributed, but ET receptors are more abundant in human heart, whereas ETg receptors constitute 70% of the ET receptors found in kidney. BQ 123 [136553-81 -6] cyclo-[D-Asp-Pro-D-Val-Leu-D-Trp], and ER 139317 (136) are selective ET antagonists. 

The spatial and steric requirements for high affinity binding to protein kinase C (PKC), a macromolecule that has not yet been crystallized, were determined. Protein kinase C plays a critical role in cellular signal transduction and is in part responsible for cell differentiation. PKC was identified as the macromolecular target for the potent tumor-promoting phorbol esters (25). The natural agonists for PKC are diacylglycerols (DAG) (26). The arrows denote possible sites of interaction. 

Diacetone-L-sorbose (DAS) is oxidized at elevated temperatures in dilute sodium hydroxide in the presence of a catalyst (nickel chloride for bleach or palladium on carbon for air) or by electrolytic methods. After completion of the reaction, the mixture is worked up by acidification to 2,3 4,6-bis-0-isoptopyhdene-2-oxo-L-gulonic acid (2,3 4,6-diacetone-2-keto-L-gulonic acid) (DAG), which is isolated through filtration, washing, and drying. With sodium hypochlorite/nickel chloride, the reported DAG yields ate >90% (65). The oxidation with air has been reported, and a practical process was developed with palladium—carbon or platinum—carbon as catalyst (66,67). The electrolytic oxidation with nickel salts as the catalyst has also... 

DAG is treated with ethanol and hydrochloric acid in the presence of inert solvent, eg, chlorinated solvents, hydrocarbons, ketones, etc. The L-ascorbic acid precipitates from the mixture as it forms, minimising its decomposition (69). Cmde L-ascorbic acid is isolated through filtration and purified by recrystallization from water. The pure L-ascorbic acid is isolated, washed with ethanol, and dried. The mother Hquor from the recrystallization step is treated in the usual manner to recover the L-ascorbic acid and ethanol contained in it. The cmde L-ascorbic acid mother Hquor contains solvents and acetone Hberated in the DAG hydrolysis. The solvents are recovered by fractional distillation and recycled. Many solvent systems have been reported for the acid-catalyzed conversion of DAG to L-ascorbic acid (46). Rearrangement solvent systems are used which contain only the necessary amount of water required to give >80% yields of high purity cmde L-ascorbic acid (70). 

The DAG conversion to L-ascorbic acid also can occur by a base-catalyzed mechanism. Methyl 2-oxo-L-gulonate (methyl DAG) is converted, on treatment with sodium methoxide, to sodium-L-ascorbate, which is then acidified to L-ascorbic acid. Various solvent systems have been evaluated and reported (46). 

Excitation of smooth muscle via alpha-1 receptors (eg, in the utems, vascular smooth muscle) is accompanied by an increase in intraceUular-free calcium, possibly by stimulation of phosphoUpase C which accelerates the breakdown of polyphosphoinositides to form the second messengers inositol triphosphate (IP3) and diacylglycerol (DAG). IP3 releases intracellular calcium, and DAG, by activation of protein kinase C, may also contribute to signal transduction. In addition, it is also thought that alpha-1 adrenergic receptors may be coupled to another second messenger, a pertussis toxin-sensitive G-protein that mediates the translocation of extracellular calcium. 

Figure 5.7 Separation of tangeretin and heptamethoxyflavon by recycle HPLC R, recycle C, collected 1, tangeretin 2, heptamethoxyflavon. Reprinted from Essenze Derivati Agrumari, 63, L. Mondello et al., Tsolamento di polimetossiflavoni dagli olii essenziali di arancia dolce e di mandarine mediante cromatografia su colonna e HPLC semipreparativa con riciclo , pp. 395-406, 1993, with permission from Essenze Derivati Agmmari.

The kinetics of the reactive compatibilization of nylon-6-PP by acrylic acid modified PP was investigated by Dagli et al. [47]. The compatibilization reaction in this system involved the reaction between the acid group of acrylic acid modified PP and the amine group of nylon-6. A typical intensive batch mixer torque (t) vs time (t) trace for a ternary blend showing an increase in mixing torque upon the addition of PP-g-AA to a binary PP-NBR (85 7.5) blend is shown in Fig. 3. The kinetic... 

The recommendations of the International Standards Organization (ISO) covering mineral-oil lubricants for reciprocating compressors are set out in ISO DP 6521, under the ISO-L-DAA and ISO-L-DAB classifications. These cover applications wherever air-discharge temperature are, respectively, below and above 160°C (329°F). For mineral-oil lubricants used in oil-flooded rotary-screw compressors the classifications ISO-L-DAG and DAH cover applications where temperatures are, respectively, below 100°C (212°F) and in the 100-110°C range. For more severe applications, where synthetic lubricants might be used, the ISO-L-DAC and DAJ specifications cover both reciprocating and oil-flooded rotary-screw requirements. 

FIGURE 2.7 Production of second messengers inositol 1,4,5-triphosphate (IP3) and diacylglycerol (DAG) through activation of the enzyme phospholipase C. This enzyme is activated by the a- subunit of Gq-protein and also by Py subunits of Gj-protein. IP3 stimulates the release of Ca2+ from intracellular stores while DAG is a potent activator of protein kinase C. 

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